Tag Archives: Louis Pasteur

The Converging Lives of Jacques Monod, Francois Jacob, Andre Lwoff, and Albert Camus in Wartime France

In the 1950s and 1960s, two French biologists at the Pasteur Institute, Francois Jacob and Jacques Monod, explained how genes are regulated in bacteria. Their studies of the “lac operon” of E. coli indeed opened up the field of gene regulation, and were a key development in the new science of molecular biology. Their experimental findings also implied the existence of an unstable intermediate between genes and protein synthesis, which eventually led to Jacob’s discovery, in collaboration with Sydney Brenner and Matt Meselson, of messenger RNA (1).

Jacob and Monod shared in the 1965 Nobel Prize for physiology or medicine for their breakthrough studies on gene regulation. Fellow Pasteur Institute scientist, Andre Lwoff, received a share of the award for his pioneering studies on the nature of lysogeny (i.e., how a bacteriophage’s genome can be incorporated into the genome of a host bacteria, and remain latent until being activated by an inducing factor).

In 2013, evolutionary biologist Sean B. Carroll published a book—Brave Genius: A Scientist, a Philosopher, and their Daring Adventures from the French Resistance to the Nobel Prize—that relates how wartime circumstances brought together Jacques Monod and his scientific colleagues Francois Jacob and Andre Lwoff (2). But while much of that story is already known (3), Carroll also tells us of the little known, but remarkable coming together of Monod and philosopher/writer Albert Camus, one of the intellectual giants of the 20th century. Coming from very different intellectual backgrounds, Monod and Camus forged a deep friendship, united in their opposition to tyranny and oppression. Carroll’s book was the inspiration for this post.

When Albert Camus learned that he had won the Nobel Prize for Literature in October 1957, he wrote to a few well-wishers, including an old friend in Paris:

My dear Monod,

      I have put aside for a while the noise of these recent times in order to thank you from the bottom of my heart for your warm letter. The unexpected prize has left me with more doubt than certainty. At least I have friendship to help me face it. I, who feel solidarity with many men, feel friendship with only a few. You are one of these, my dear Monod, with a constancy and sincerity that I must tell you at least once. Our work, our busy lives separate us, but we are reunited again, in one same adventure. That does not prevent us to reunite, from time to time, at least for a drink of friendship! See you soon and fraternally yours.

                                                                                                                                             Albert Camus

Camus appears somewhat downcast in his note to Monod. At 43-years-in-age, he was the second youngest writer ever to receive the Nobel Prize for literature (Rudyard Kipling at 42 was the youngest), and he was worried that the ballyhoo surrounding the award might distract him from his writing. And, he was concerned that the prize might stir up additional contempt from critics of his writing, as well as from his leftist colleagues who opposed his condemnation of Soviet communism.

But, why did philosopher/writer Camus—an intimate of some of the greatest writers and artists of the mid-twentieth century, including Sartre and Picasso—write to scientist Monod, and acknowledge the special importance he placed on their friendship? Likewise, why did he assert: “I have known one true genius, Jacques Monod.” And, what is the same adventure that Camus refers to?

A brief background to our tale is as follows. In March 1939, Hitler took control of Czechoslovakia. Next, on September 1, Germany invaded Poland. On September 2nd, Poland’s allies, Britain and France, issued an ultimatum to Germany: withdraw or face war. On September 3rd, the ultimatum expired, Britain and France declared war on Germany, and the Second World War was underway; sort of. Although Germany went on to conquer Poland in a mere eight days, several months passed without further action. Then, in May 1940, Nazi Germany invaded and overran France in just six weeks. Marshall Pétain surrendered to the Germans, the French Forces were disbanded, the pro-Nazi Vichy government was put in place under former prime minister Pierre Laval and the 84-year-old Pétain, and the Nazi occupation of the defeated French nation began.

A few months before the Nazis invaded France, thirty-year old Jacques Monod was a doctoral student in zoology at the Sorbonne. [A polymath, he also founded a Bach choral group, and was an accomplished cellist, and seriously considered a career in music (4).]  But as war with Germany loomed, Monod enlisted in the army—in the communication engineers—where he thought he might use his scientific talents if war were to break out. Consequently, Monod was serving on the front lines when the Germans invaded. France suffered the most colossal military disaster in its history, and Monod returned to his studies in Paris.

Life in France grew progressively harsher under the Nazis; beginning with subjugation, and followed by deportations, enslavement, and mass murder. Early on, Monod joined one of the first units of the French Resistance; a group of ethnologists and anthropologists at the Musée de l’Homme (Museum of Man).

One of Monod’s duties for the Musée de l’Homme group was to distribute its newspaper, at night. This seemingly simple task was extremely dangerous since capture could mean deportation to a concentration camp or execution. Monod, in fact, had several close escapes. On one occasion, the Gestapo raided his laboratory at the Sorbonne. Fortunately, since they were fearful of the viruses and radioactive isotopes in the lab, they didn’t search it as thoroughly as they might have. Otherwise, they might have found sensitive documents that Monod would hide inside the leg of a mounted giraffe outside his office. In any case, the Germans soon routed the short-lived Musée de l’Homme group

Monod’s wife, Odette, was the granddaughter of Zadoc Kahn, the former chief rabbi of France. Since the Vichy government soon began enacting Nazi policies, including anti-Jewish laws, and because of homegrown French anti-Semitism, Odette sought refuge for herself, and for her and Jacque’s twin sons (born in August 1939, four weeks before the war broke out), under assumed names, in a village outside of Paris. Meanwhile, Jacques had to register with the Vichy authorities as the spouse of a Jewish person.

With Odette and the children concealed, Monod joined the most militant unit in the Resistance; the Communist-led Franc-Tireurs (Free Shooters) group. Monod was not then a Communist Party member. Nonetheless, he joined the Franc-Tireurs since they actually were fighting the Germans—assassinating German officers in the streets and carrying out sabotage. One of his missions for the Franc-Tireurs took him to Geneva—through the Alps to avoid arrest—to request money for arms from the United States Office of Strategic Services; the precursor of the present Central Intelligence Agency.

By this time, Monod had gone completely underground. He wore a disguise during the day, slept in safe houses at night, and stayed away from his laboratory at the Sorbonne. But then, Andre Lwoff, the head of microbial physiology at the Pasteur Institute, offered Monod a refuge and a place to work in his laboratory at the Pasteur Institute. Monod then led a double-life. By day, as Monod, he worked on his experiments at the Pasteur Institute. At night, he carried out his duties for the Franc-Tireurs, as “Marchal” (from a character in a novel by Stendhal), and as  commander “Malivert.” [Lwoff too had been active in the Resistance, gathering intelligence for the Allies, while also hiding downed American airmen in his apartment.]

Jacques Monod’s identity card for the French Forces of the Interior (FFI), in his nom de guerre ‘Malivert.’

Monod was resolutely committed to the Resistance, while also maintaining a productive research program. At the Pasteur Institute, he and his student, Alice Audureau, made key discoveries that would lead to the later breakthroughs he would make with Jacob. [For instance, Monod and Audureau discovered mutations in E. coli genes that caused the induction of lactose metabolism; a finding that would have important implications concerning gene action and regulation.] Moreover, he was devoted to Odette and their twin sons, and managed to make frequent clandestine visits to see them.

Monod took on increasing responsibilities in the Franc-Tireurs, as more members of the group were discovered and executed by the Germans. In fact, by the time of the allied invasion of Normandy in June 1944, Monod, had become chief of staff of the operations bureau for the National Resistance Organization; a position from which his three predecessors had disappeared (4). As such, Monod prepared battle plans for the allied surge to Paris. He also arranged parachute drops of weapons, railroad bombings, and mail interceptions.

Interestingly, Monod also recruited to the Resistance renowned French chemist, John Frédéric Joliot-Curie (Aside 1), who devised a unique recipe for Molotov cocktails, which were the Resistance’s principal weapon against German tanks. In addition, Monod organized the general strike that facilitated the liberation of Paris. Then, after the liberation of Paris, he became an officer in the Free French Forces, and a member of General de Lattre de Tassigny’s general staff.

[Aside 1: John Frederick Joliet was working as an assistant to Marie Curie, when he married Marie’s daughter, Irene. Afterwards, both John Frederick and Irene changed their surnames to Joliot-Curie. In 1935, the couple was awarded the Nobel Prize in Chemistry for their seminal research on radioactivity. John Frederick then worked at the Collège de France on controlled chain reactions. His work on that was cited by Albert Einstein in his famous 1939 letter to President Franklin Roosevelt, warning Roosevelt of the possibility of a nuclear weapon: “In the course of the last four months it has been made probable through the work of Joliot in France as well as Fermi and Szilard in America—that it may be possible to set up a nuclear chain reaction in a large mass of uranium, by which vast amounts of power and large quantities of new radium-like elements would be generated. Now it appears almost certain that this could be achieved in the immediate future…This new phenomenon would also lead to the construction of bombs…” The Nazi invasion ended Joliet-Curie’s nuclear research. Nevertheless, he managed to smuggle his research notes out of France to England.]

Francois Jacob, a Jewish, nineteen-year old 2nd-year medical student, was planning on a career in surgery when the German occupation of France began in the Spring of 1940. Resolved to carry on the fight against Hitler, Jacob left medical school and boarded one of the last boats for England. In London, he was one of the first of the French to join Charles de Gaulle’s Free French Forces. He wanted to enroll in a combat unit, but, despite his incomplete medical training, he was commissioned as a medical doctor, and then served as a medical officer in North Africa. His surgical career was prematurely cut short in August 1944, when he was severely wounded at Normandy; by a bomb dropped from a German Stuka dive bomber. At the time, he was tending to a dying officer.

For their wartime service, Jacob and Monod were each awarded France’s highest honors for valor. Jacob was awarded the Cross of Liberation, as well as the Légion d’Honneur and the Croix de Guerre. Monod likewise received the Légion d’Honneur and the Croix de Guerre, as well as the American Bronze Star.

Unable to practice surgery after the war because of his wartime wounds, Jacob eventually turned to a career in science. He was accepted at the Pasteur Institute, where he beseeched Lwoff (Monod’s host at the Pasteur Institute) to serve as his mentor. Lwoff rebuffed Jacob several times, but finally agreed to take the young doctor under his wing. Then, in the cramped quarters of Lwoff’s laboratory at the Pasteur, Jacob and Lwoff’s student, Elie Wollman, began a fruitful collaboration that produced key insights into bacterial conjugation and the regulation of lysogeny (Aside 2). After that, Jacob and Monod forged their extraordinary collaboration that would lead to their Nobel Prizes. Note that Jacob’s earlier work with Wollman, on lysogenic induction, would provide the underpinning for his later work on gene regulation with Monod (3).

[Aside 2: Elie Wollman, born in 1917, was Jewish. In 1940, he escaped from the Nazis in Paris and then worked underground in the Resistance as a physician. His parents, Eugene and Elizabeth Wollman, were Pasteur Institute scientists who were seized by the Nazis in 1943 and sent to Auschwitz. They were never heard from again (3).]

In December of 1939, our other main protagonist, twenty-six-year-old Albert Camus, was an unknown, aspiring writer, working as a reporter and editor for a newly founded left-wing newspaper, Alger Republican, in his native Algeria; which was then under French control. Camus was completely opposed to the war, which he saw as “another unnecessary, avoidable, disastrous, absurd chapter of history that would consume the lives of those who did not make it or wish for it.” His antiwar editorials in the Alger Republican outraged French government officials who were calling for unity against Germany. The government finally shut down the newspaper, leaving Camus unemployed. So, Camus returned to France, where the prospects for employment were now better because wartime mobilizations had left many businesses shorthanded. See Aside 3.

[Aside 3: Camus started writing The Stranger while in Algeria, basing it on people and places he knew there. His purpose in The Stranger was to express how one might react to his philosophical notion of the “absurd”—the disconnect between our desire for a rational existence, and the actual world, which appears confused and irrational—in the form of a novel. Meursault, the narrator, and principle character in The Stranger, shows no grief over his mother’s death, no remorse over having committed an unintended murder, and no belief or interest in god. Even while Meursault was awaiting the guillotine, he was reconciled to “the tender indifference of the world.” Meursault’s honesty in describing his feelings makes him a ‘stranger’ in the setting of the novel, and seals his fate.]

Camus was not called up for military service when he returned to France, because he had contracted tuberculosis in Algeria, when he was 17 (Aside 4). Nonetheless, he twice attempted to enlist—the second time when the French Army was on the verge of surrender to the Nazis—to express his solidarity with those who were being drafted. In any case, the military rejected him each time because of his tuberculosis. So, he managed to get a job in Paris as a layout designer for the newspaper Paris-Soir.

[Aside 4: In the pre-antibiotic era, tuberculosis was often fatal, and the 17-year-old Camus indeed had a close brush with death. That experience had a profound effect on the “precocious philosopher,” who made notes on the question of “how, in the light of the certainty of death, one should live life.”]

Parisians began fleeing from their city when the German invasion began in May of 1940. Then, in June, as the Germans were on the verge of entering Paris, the stream of refugees became a flood, with about 70 percent of the city’s metropolitan population of nearly five million eventually taking flight from the city. All Parisian newspapers stopped publishing. However, Paris-Soir hoped to resume its operations in the south, with a reduced staff. Thus, Camus joined the stream of refugees, driving an automobile (almost all the paper’s regular drivers had been drafted), with a Paris-Soir executive as his passenger. After Camus and his passenger were well on their way, Camus suddenly realized that in the rush to vacate from Paris, he may have left his manuscript for The Stranger behind in his room. “He jumped out of the car and threw open the trunk, and was relieved to find in his valise the complete text of The Stranger.” See Aside 5.

[Aside 5: In 1885, Joseph Meister, at nine-years-of-age, was the first recipient of Louis Pasteur’s rabies vaccine and, as an adult, was caretaker of the Pasteur Institute; a position that he still held at the start of the Nazi occupation in 1940.  In despair over the fall of France, and wrongly believing that German bombs killed his family after he sent them away, he went to his apartment, closed the windows, and turned on the gas in his stove (5, 6).]

Camus went with Paris-Soir to Clermont-Ferrand. There, the paper began to publish again, using printing facilities made available by Pierre Laval, the former premier, and now architect of the Petain Vichy government. But with the paper now under Laval’s control, it began publishing anti-Semitic articles, and other articles in support of the Vichy government. Camus did not write any of these items. In any case, he was let go by Paris-Soir after the draftees of the 1940s were discharged and could return to work. Camus then went back to Algeria, where he completed The Stranger.

In 1942, with The Stranger about to be published in France, Camus suffered a nearly fatal relapse of his tuberculosis. He wanted to return to France for treatment in the Massif Central mountain range, but several months would pass before Algerian authorities gave him permission to do so. Then, upon returning to Paris, he would have a purpose that would totally engage him.

One night, under an assumed name (because of the need for secrecy in the Resistance), Camus stole into the clandestine headquarters of Combat (the journalistic arm and voice of the French Resistance), to implore the staff to take him on since he “had already done a little journalism” and would be happy to help in any way. Like Monod, Camus then led a double-life, carrying out his duties at Combat, as “Bauchard.” At first, he helped to select and edit articles, and prepare the paper’s layout. Then, in 1943 he became the paper’s editor, and wrote stirring editorials, exhorting Frenchmen to act against the German occupiers. By the time The Stranger was published in 1942, his recognition as Camus led to his acceptance into the literary and artistic circle that included Sartre, Simone de Beauvier, and Picasso.

Albert Camus’s false identity card, in the name of Albert Mathé, writer. All of the information on the card — birthdate, place, parents — is false.

Camus was suffering from recurrent bouts of tuberculosis all the while that he was carrying out his work at Combat. Nonetheless, as Camus, he also published his essay, The Myth of Sisyphus, which, like The Stranger, contemplates the experience of the Absurd (see Aside 3, above). And he also wrote The Plague, which depicts a city’s response to an outbreak of bubonic plague; perhaps a metaphor for the Nazi occupation. Remarkably, no one at Combat had an inkling that the man who at first had been editing and arranging pages for them as Bauchard was in fact the now renowned Camus. See Aside 6.

[Aside 6: Among laypeople, Jacques Monod is perhaps best known for his “popular” book, Chance and Necessity, published in 1970, and a bestseller in its day. Monod’s Chance and Necessity, and Camus’ The Myth of Sisyphus, are each relevant here because they point up how Camus influenced Monod’s view of the meaning of life. While Camus took a philosophical approach to that issue, Monod’s assessment was also informed by his knowledge of life’s fundamental molecular mechanisms. With the 1953 discovery by Watson and Crick of the molecular structure of DNA, it was apparent how accidental, random, unpredictable mutations in the sequence of bases in DNA were the source of all biological diversity. Thus, Monod knew that all living forms, including humans, are the products of chance genetic mutations and circumstances: “Man at last knows that he is alone in the unfeeling immensity of the universe, out of which he emerged only by chance. Neither his destiny nor his duty have been written down. The kingdom above or the darkness below: it is for him to choose.” [Monod’s title, Chance and Necessity, is from Democritus’ dictum “Everything in the universe is the fruit of chance of chance and necessity.”]  

That we live in a world that is indifferent to our hopes and suffering was the reason for Monod to inquire into the meaning of life, which, for Camus, was “the most urgent of questions.” Camus was often branded an existentialist, but unlike many contemporary existentialist thinkers, Camus vehemently rejected nihilism. In The Myth of Sisyphus, he wrote that Sisyphus gave his life meaning by choosing to believe that he remained the master of his own fate, even though he was condemned to rolling his rock uphill each day, only to have it roll back down.

On the opening page of Chance and Necessity, Monod includes a lengthy quotation from the closing paragraphs of The Myth of Sisyphus. “The struggle itself towards the heights is enough to fill a man’s heart…One must imagine Sisyphus happy.” Camus is advocating that we oppose the certainty of death in an uncaring Universe by living life to the fullest. For Monod, life is like Sisyphus, pushing its rock uphill. The end might be bleak, but “the struggle towards the heights is enough to fill a man’s heart.”]

By 1944, the liberation of Paris was imminent, Combat went from a monthly publication to a daily one, and the paper chanced to circulate in the open. Camus was still writing his editorials anonymously. And when his identity was finally revealed, his inspiring, eloquent words resulted in his widespread public acclaim.

Monod and Camus were very likely aware of each other at this point in our saga, but they had not yet met. Their meeting would happen after the liberation of France, and it would be in response to a new totalitarian threat; from the Soviet Union. It transpired as follows.

In 1948, Monod was working full-time on his research at the Pasteur Institute, when events in the Soviet Union moved him to write a stirring editorial that appeared on the front page of Combat. [Camus had left Combat the previous year, after it became a commercial paper.] Monod’s piece was in response to a pseudoscientific doctrine advanced by Stalin’s head of Soviet agriculture, Trofim Lysenko, which asserted that organisms could swiftly change their genetic endowment in response to a new environment. [Lysenko’s doctrine is reminiscent of discredited Lamarckian doctrine, also known as heritability of acquired characteristics—i.e., the premise that if an organism changes to adapt to an environment, it can pass on those changes to its offspring.] Lysenko based his doctrine on his purported discovery of a means to enable winter wheat to be sown in the spring.

Stalin embraced Lysenkoism—during an acute grain shortage in Russia—since it was in accord with his ideology to create the New Soviet Man. Stalin also banned all dissent against Lysenko’s doctrine. Consequently, traditional Russian geneticists were exiled or murdered, Mendelian genetics was no longer practiced in the Soviet Union, and Soviet agriculture suffered severely.

Monod was roused to write his editorial after French Communist newspapers began to widely disseminate Lysenko’s doctrine in France. One Party newspaper proclaimed Lysenko’s discovery “A Great Scientific Event,” and further asserted that the notion of evolution by natural selection was a racist form of thinking, in harmony with Nazi doctrine (7). Another Party newspaper condemned Mendelian genetics for being “bourgeois, metaphysical and reactionary,” while claiming that it must be false because it is reactionary; having been invented by an Austrian monk. In Contrast, Lysenkoism is true because it is progressive and proletarian.

A Party member’s position on Lysenko indeed had become a gauge of his commitment to Stalin’s Soviet cause. But for Monod, the Soviet embrace of Lysenko was “senseless, monstrous, unbelievable.” As expected, Monod’s article was strongly condemned by the powerful French Communist Party, which enjoyed broad support from both intellectuals and workers; many of whom saw the Soviet Union as a model for a French socialist state. In any case, the Party’s strong backlash inspired Monod to “make his life’s goal a crusade against anti-scientific, religious metaphysics, whether it be from Church or State.” Importantly, a separate consequence of the Lysenko affair was that it influenced François Jacob to focus his research in the field of genetics. See Aside 7.

[Aside 7: Ironically, the observation that Jacob and Monod initially set out to explain looked remarkably like Lysenkoism. When E. coli are fed a solution of glucose and lactose, they grow rapidly until glucose—their preferred carbon source—is depleted. Only then, they turn to metabolizing lactose. But, in contrast to Lysenko’s doctrine, Jacob and Monod showed that when E. coli “adapts” to lactose, it does so without changing its genes. Instead, the genes encoding the enzymes that metabolize lactose lie dormant until lactose induces them, under conditions in which glucose is not available. That is, Jacob and Monod determined that lactose regulates lactose metabolism in the cell by acting as an inducer of genes that already exist in the cell; as opposed to lactose causing the cell to undergo a Lamarckian acquisition of a genetic characteristic. In so doing, Jacob and Monod created the now well-established paradigm of inducers, regulators, regulator genes, and operators.]

While Monod was crusading against Lysenkoism, Camus was having his own feud, in public, with Sartre, who had chastised him for his anti-Soviet stance. Camus had once been a Communist, in Algeria, mainly because he was troubled by the way in which the European French treated the native Algerians. However, he was never very sympathetic to the Marxist cause. Monod too had once been a member of the Communist Party; but only because it enabled him to have a voice in the running of the Resistance. In any case, Camus seized upon Monod’s condemnation of Lysenkoism in his feud with Sartre.

Our two main protagonists finally met when Camus co-founded the anti-Stalin, anti-totalitarian Groupes de Liaison Internationale. Monod attended one of the group’s meetings. There, he, and Camus, discovering that they shared much in common, forged their friendship. Carroll writes: “Camus, who so treasured the sense of solidarity that existed among the Resistance, had in Monod a new comrade who shared both the deep bond of that wartime experience and an unqualified opposition to a new common enemy.”

As noted, Monod’s views on the meaning of life owed much to Camus. Likewise, Camus learned from Monod. Camus not only used Monod’s case against Lysenko in his dispute with Sartre, but he also “borrowed” from Monod in The Rebel; in which Camus argued that revolution inevitably leads to tyranny. In any event, after Camus and Monod had separately fought the Nazis, they were now united against another oppressor—the totalitarian state run by Stalin. [Camus’ anti-Soviet stance cost him the friendships of many French intellectuals on the left. He and Sartre never spoke to each other again.]

Monod was also troubled by the situation of scientists working under Eastern European Soviet regimes. In 1959, he organized the escape into Austria of Hungarian biochemist Agnes Ullman (who participated in the failed Hungarian uprising of 1956), and her husband, also a scientist. Earlier, in 1958, Agnes Ullman managed to visit Monod at the Pasteur Institute, and confided to him that she and her husband wanted to defect from Hungary. Monod maintained contact with the Ullmans in Hungary, using coded messages, written in invisible ink, which turned blue when exposed to iodine. The Ullmans finally crossed into Austria, hidden underneath a bathtub, in a compartment of a pull-along camping trailer. See Aside 8.

[Aside 8. Agnes Ullmann, became Monod’s long-time close collaborator at the Pasteur Institute. Now retired, she was carrying out research at the Pasteur Institute as recently as 2012; 53 years after her rescue from Hungary. At the Institute, she collaborated with Monod on characterizing the lac operon promoter, on complementation between β-galactosidase subunits, and on the role of cAMP in overcoming the repressive effect of glucose (catabolite repression) on lactose metabolism in E. coli.]

There are numerous other instances in which Monod stepped forward to fight injustice and defend human rights. In 1952, he wrote a letter in Science that might have been “ripped from today’s headlines.” It protested the U.S. government’s rejection of visa requests for himself and other Europeans who had once been Communists. Monod also condemned the treatment of Jews in the Soviet Union, while continuing to speak out against Soviet totalitarianism in general. And, in 1965, shortly after Monod, Lwoff, and Jacob received word of their Nobel Prizes, they publicly appealed to the French government to allow the use of contraceptives, and the legalization of abortion. See Aside 9.

[Aside 9: Jacob too was devoted to the defense of human rights. He chaired a committee of the French Academy of Sciences that supported persecuted scientists living under totalitarian regimes, and he worked for the release of those who had been imprisoned for their political views. Moreover, he forcefully advocated for the public support of the biological and medical sciences. What’s more, Jacob also had a distinguished writing career that produced a series of acclaimed books, including The Logic of Life: A History of Heredity; Of Flies, Mice and Men; The Possible and the Actual, and his memoir, The Statue Within. In Joshua Lederberg’s review of the latter for The Scientist, he stated:As a work of literature, it evokes unmistakable overtones of Rousseau, Proust, and Sartre.” In Jon Beckwith’s view, all of Jacob’s books are “written in a fluid and elegant style” Others refer to the “clarity and grace” of Jacob’s writing. See reference 8 for more on Jacob.]

In 1966, Martin Luther King Jr. and Harry Belafonte visited France to raise funds for the Southern Christian Leadership Conference (SCLC). Remarkably, Monod was chosen to introduce King to a crowd of 5,000 people at Paris’ Palais des Sports. Belafonte was introduced by French singer and actor Yves Montand (9).

Coretta Scott King shaking hands with Jacques Monod, as Martin Luther King Jr. looks on. From l-r: French actress Simone Signoret, Harry Belafonte, French actor and singer Yves Montand. 29 March 1966, at a meeting of the “Movement for the Peace.”

The intellectual lives of Monod and Camus played out in entirely different areas. Yet the parallels were striking. Each, in his way, searched for meaning in life. Moreover, each put his life on the line to oppose ignorance, injustice, and totalitarianism. And, it is clear from their correspondences that they were dear to each other. Here is the note from Monod that elicited Camus’ response at the top of this post.

My dear Camus,

My emotion and my joy are profound. There were many times when I felt like thanking you for your friendship, for what you are, for what you managed to express with such purity and strength, and that I had likewise experienced. I wish that this dazzling honor would also appear to you, in some small part, as a token of friendship and of personal, intimate recognition. I would not dare coming to see you right now, but I embrace you fraternally.

Jacques Monod

This piece ends with a few personal thoughts. Jacques Monod was a Nobel Prize-winning scientist, a hero of the French Resistance, a rescuer of persecuted scientists from behind the Iron Curtain, and a leading voice against tyranny and oppression. And, he was also blessed with dashing good looks. I remember well the women among my fellow graduate students in the 1960s finding him to be very attractive. But, on a more serious note: Today, when political and religious blocs dismiss evidence-based science in favor of alternative ‘facts’ in order to advance their ideologies, and when they are tacitly aided by a press that all too often gives equal validity to all points of view, and while scientists seem to be groping for an effective response, one can hope that scientists with the courage, eloquence, and eminence of Jacques Monod and Francois Jacob might emerge to take up the cause of science and reason. Meanwhile, it is especially important for young scientists, and the public, to be aware of the examples set by these men. See Aside 10.

[Aside 10: The following is from a March 8, 2017 editorial in Nature.  “Last week, state legislators in Iowa introduced a bill that would require teachers in state public schools to include ‘opposing points of view or beliefs’ in lessons on topics including global warming, evolution and the origins of life… Since last month, Indiana, Idaho, Alabama, Texas, Oklahoma and Florida have all introduced and discussed similar tweaks to the way in which they want to educate their children… Although these proposed changes are typically presented by their supporters as giving teachers the chance to discuss genuine scientific controversies, in truth they are (very) thinly veiled attempts to pursue political and religious agendas that have no place in school science lessons — for whatever age. They seek to import the alternative facts and misleading rhetoric of the new federal government and to impose it on children who deserve much better from those elected to serve them.”]

References:

  1. A Most “Elegant” Experiment: Sydney Brenner, Francois Jacob, Mathew Meselson, and the Discovery of Messenger RNA , Posted on the blog October 6, 2016.
  2. Sean B. Carroll, Brave Genius: A Scientist, a Philosopher, and their Daring Adventures from the French Resistance to the Nobel Prize, Crown, 2013.
  3. Genealogies and a Selective History of Lysogeny: Featuring Friedrich Loeffler, Emile Roux, Andre Lwoff, Elie Wollman, and Francois Jacob, Posted on the blog January 28, 2015 (8).
  4. Agnes Ullmann, In Memoriam: Jacques Monod (1910–1976), Genome Biology and Evolution 3:1025-1033. 2011, DOI: https://doi.org/10.1093/gbe/evr024.
  5. Louis Pasteur: One Step Away from Discovering Viruses, Posted on the blog January 7, 2015.
  6. Dufour, H. D., and S. B. Carroll, History: Great myths die hard, Nature 502:32–33, 2013.
  7. John Marks, Jacques Monod, François Jacob, and the Lysenko Affair: Boundary Work, L’Esprit Créateur: Genetics and French Culture. 52:75-88.
  8. Beckwith, J., and M. Yaniv, Francois Jacob (1920-2013), Current Biology 23:R422-R425, 2013.
  9. Remembering Dr. Martin Luther King Jr., CBS Minnesota, January 19, 2013, 3:51 PM.
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Elie Metchnikoff: The “Father of Innate Immunity”

The legend of Isaac Newton being struck on the head by a falling apple has long been enshrined in scientific lore. Likewise, there is the tale of Mendeleev suddenly grasping the relationship between the elements (i.e., discovering the Periodic Table) while struggling over how to organize them for a chemistry textbook he was writing. And, there is the myth of Kekule envisioning the benzene ring structure while dreaming of a snake grasping its own tail. Also, there are the fables of Ben Franklin and his Kite, Darwin and his finches, and Galileo dropping objects from the Leaning Tower of Pisa, among others.

Here we have the tale of Russian zoologist Elie Metchnikoff (1845-1916) who, in 1882, discovered leukocyte recruitment and phagocytosis as key elements in the body’s natural defenses. The mythical aspect of Metchnikoff’s discovery is that it allegedly happened while he was experimenting on starfish larvae. Metchnikoff was awarded a share the 2008 Nobel Prize in Physiology or Medicine for his discovery. German microbiologist Paul Ehrlich shared the 2008 award for his pioneering discoveries in humoral immunity.

Elie Metchnikoff
Elie Metchnikoff

We are fortunate to have Metchnikoff’s account of his 1882 epiphany, written in his own words shortly after he was awarded the Nobel Prize in 2008 (1).

“One day, as the whole family had gone to the circus to see some exceptional trained monkeys, while I had remained alone at my microscope and was following the life of motile cells in a transparent starfish larva, I was struck by a novel idea. I began to imagine that similar cells could serve the defense of an organism against dangerous intruders. Sensing that I was on to something highly interesting, I got so excited that I started pacing around, and even walked to the shore to gather my thoughts.

I hypothesized that if my presumption was correct, a thorn introduced into the body of a starfish larva, devoid of blood vessels and nervous system, would have to be rapidly encircled by the motile cells, similarly to what happens to a human finger with a splinter. No sooner said than done. In the shrubbery of our home, the same shrubbery where we had just a few days before assembled a ‘Christmas tree’ for the children on a mandarin bush, I picked up some rose thorns to introduce them right away under the skin of the superb starfish larva, as transparent as water. I was so excited I couldn’t fall asleep all night in trepidation of the result of my experiment, and the next morning, at a very early hour, I observed with immense joy that the experiment was a perfect success! This experiment formed the basis for the theory of phagocytosis, to whose elaboration I devoted the next 25 years of my life.

So, at a time when virtually nothing was known about the body’s natural defenses, Metchnikoff proposed that the mobile cells (later dubbed “phagocytes” or cell-eaters), which gathered around the thorns in the starfish larvae, were agents of healing. Moreover, he proposed that those cells are the first line of an organism’s defense against invading pathogens. Metchnikoff’s use of starfish larvae in his breakthrough experiment owed to his interest in marine invertebrates which, in turn, reflected his broad interest in natural history.

Metchnikoff’s passionate interest in science, natural history, and marine invertebrates developed early in his life. In 1870, when he was barely 25 years-old, he was appointed a professor of zoology and comparative anatomy at the University of Odessa; a position he resigned in 1882 because of limited research opportunities in Odessa, and because of political instability in the Ukraine after the assassination of Alexander II. Metchnikoff’s pioneering experiments that year were carried out at a private laboratory in Messina. [Later, during the Soviet Era, Odessa University was renamed Odessa I.I. Mechnikov National University, in Metchnikoff’s honor.]

In 1888 Louis Pasteur recruited Metchnikoff to the Pasteur Institute, where he would spend the remainder of his career. There, under the influence of Pasteur and Emile Roux (with whom he developed a close friendship), Metchnikoff turned his attention from simple organisms to experimental infectious disease and immunity.

By the late 1880s, Metchnikoff’s hypothesis that leukocyte recruitment and phagocytosis played a key role in host defense was garnering considerable attention. However, much of that attention was hostile, mainly because Paul Ehrlich, in Germany, was concurrently promoting the role of antisera in the body’s defenses.  The resulting feud between French scientists at the Pasteur Institute and Ehrlich’s colleagues in Germany was dubbed the “Immunity War.” [The “Immunity War” also may have reflected nationalistic feelings left over from the quite real Franco-Prussian war of July 1970 to May 1971.]

It was not until after Metchnikoff and Ehrlich shared their 1908 Nobel award that immunologists recognized that Metchnikoff’s phagocytes were a feature of “innate immunity,” while Ehrlich’s antibodies were a feature of “adaptive immunity.” Eventually both schools of thought would be integrated into our modern understanding of immunity. Metchnikoff would be recognized as the “Father of Innate Immunity,” while Ehrlich would be recognized as the pioneer of adaptive immunity (see the Aside). But, Metchnikoff’s early dispute with Ehrlich may be one reason why he avoided attending the 1908 Nobel Prize award ceremony. Metchnikoff presented a delayed Nobel lecture in Stockholm in 1909.

[Aside: Innate immunity is so named because it is present at birth and remains unchanged throughout life. It is the body’s first response to an invasive pathogen. Innate immunity is fast because it recognizes molecular patterns that are characteristic of broad classes of microorganisms; doing so via receptors that are encoded in the germ line. In contrast, the adaptive immune system is highly specific, recognizing determinants that are unique to each invader; doing so via receptors that are not encoded in the germ line. The adaptive immune system also has a memory. The price for the adaptive system’s specificity is that activation can take 1 week or longer. Innate immunity is the more primitive of these systems. It is present in primordial invertebrates, including insects, worms and mollusks. In contrast, adaptive immunity is seen only in vertebrates.]

How true to fact is the starfish-based tale of Metchnikoff’s discovery? A recent review by Siamon Gordon (Oxford professor of cellular pathology) suggests that Metchnikoff’s own personal account may not be entirely accurate (2).  For instance, a review of the early scientific literature shows that at the time of Metchnikoff’s discovery, phagocytosis had already been described by others.  Intriguingly, a description of phagocytosis appeared in the 1862 novel Fathers and Sons by Turgenev; an author admired by Metchnikoff. In Turgenev’s novel, “the description is given by a nihilist doctor, Yevgeny Bazarov, who, like Metchnikoff, used the microscope to make his own observations (2).”

Nonetheless, Gordon asserts that Metchnikoff indeed carried out the starfish experiments which led to the discovery. Moreover: “What distinguishes his (Metchnikoff’s) discovery from other early descriptions is that he followed up the initial observation with a program of striking experiments, which convinced him that this was a far-reaching process of general biological significance (2).” [Another review by Gordon summarized Metchnikoff’s many considerable contributions (3), some of which are noted below (see Note).]

The “myth” of Metchnikoff’s discovery, like all such myths, often convey a misimpression of the nature of scientific discovery, since they do not sufficiently acknowledge the intense efforts, sustained over considerable periods of time, which are generally necessary to produce major breakthroughs. But, these myths are fun and they do enhance the lay-public’s awareness of science.

Metchnikoff became somewhat of a public celebrity in his later years when he advocated eating yogurt to promote good health and long life (4). Apropos our larger story, Metchnikoff’s promotion of yogurt consumption was inspired by his interest in phagocytes. It was based on his beliefs that 1) the infirmities of old-age happen when phagocytes are transformed from defenders against infection into destroyers of healthy tissue by autotoxins (i.e., toxins that harm the organisms in which they are produced) derived from “putrefactive bacteria” residing in the colon, 2) that these degenerative changes could be prevented by inhibiting the colon’s putrefactive bacteria, and 3) that the host-friendly lactate-producing bacteria in yogurt would inhibit the putrefactive bacteria in the colon. [Metchnikoff regarded the colon as a “vestigial cesspool,” which does little more than provide a reservoir for putrefactive bacteria.]

Metchnikoff’s yogurt-eating regimen attracted numerous adherents for a time, but it eventually fell out of favor (indeed it even was satirized), since the premises on which it was based were never verified. Nonetheless, the medical community has recently been using Lactobacillus acidophilus to effectively treat several conditions, including pediatric antibiotic-associated diarrhea, acute infectious diarrhea, and persistent diarrhea in children. So, might Metchnikoff also be viewed as the “father” (or grandfather perhaps) of the current probiotics craze?

References:

1. Metchnikoff E: My stay in Messina (Memories of the  past, 1908); in Souvenirs, Editions en Languese Etrangeres. Moscow, 1959 (translated from the French by Claudine Neyen). (w.karger.com/doi/10.1159/000443331)

2. Gordon S. 2016. Elie Metchnikoff, the Man and the Myth. Journal of Innate Immunity, 8:223-227.

3. Gordon S. 2008. Elie Metchnikoff: Father of natural immunity. European Journal of Immunology, 38:3257-3264.

4. Mackowiak P. 2013. Recycling Metchnikoff: Probiotics, the Intestinal Microbiome and the Quest for Long Life. Frontiers in Public Health. 1-3.

Note: “His (Metchnikoff’s) notable observations include proof that organisms were taken up by an active process, involving living, and not just scavenged dead organisms; acidification of vacuoles, digestion and destruction of degradable particles including many infectious microbes including bacteria, spirochaetes and yeasts; uptake of host cells, e.g. erythrocytes, often nucleated for ready identification, from diverse species, as well as spermatocytes; and carmine dye-particles, used as an intravital marker of phagocytosis. Metchnikoff emphasized observations in living systems, combining microscopy and staining with neutral red and other histological labels to evaluate the acidity of vacuoles, viability and fate of ingested organisms. The bacteria examined included Cholera vibrio, Bacillus pyocyaneum, Bacillus anthracis and its spores, Mycobacterium (human, avian and bovine), plague bacilli, Streptococci and Gonococci, and some of these were studied in combination. He demonstrated killing by leukocytic enzymes (‘cytase’). Metchnikoff made important contributions to understanding the entire process of inflammatory recruitment, described at length in his lectures on comparative inflammation. He observed diapedesis through vessel walls, aggregation of leukocytes at sites of inflammation and their tendency to fuse, and he dissected the role of endothelial, epithelial and mesenchymal cells, as well as of lymphatic drainage and nervous elements in the classic hallmarks of inflammation (oedema, rubor, calor, dolor, loss of function) and repair. By using simple organisms, he discovered the central role of phagocytosis in diverse biologic models. This work led naturally to studies on the clearance and fate of organisms after experimental administration via a variety of routes, e.g. intravenous, intraperitoneal, subcutaneous and even the anterior chamber of the eye (3).”

 

Hilary Koprowski: Genesis of a Virologist

Several years before Jonas Salk and Albert Sabin developed their famous polio vaccines, Hilary Koprowski (1916-2013) in fact developed the world’s first effective, but much less well known polio vaccine (1, 2). Koprowski’s vaccine was used world-wide, but it was never licensed in the United States, ultimately losing out to Sabin’s vaccine.

Koprowski’s reputation was tarnished in 1950, when he tested his live polio vaccine on 20 children at Letchworth Village for mentally disabled children, in Rockland County, NY; an episode recounted in a recent posting Vaccine Research Using Children (1). Koprowski reported on the Letchworth Village trials at a 1951 conference of major polio researchers. Although his vaccine induced immunity in the children, and caused no ill effects, many scientists in the audience were horrified that he actually tested a live polio vaccine in human children. Afterwards, Sabin shouted at him: “Why did you do it? Why? Why?”

Although Koprowski’s polio vaccine was supplanted by the Salk and Sabin vaccines, his demonstration, that a live polio vaccine could be safe and effective, paved the way for Sabin to develop his live polio vaccine. Moreover, Sabin developed his vaccine from a sample of attenuated poliovirus that he received from Koprowski.

There is much more to tell about Koprowski. This posting relates some of the remarkable earlier events of his life, including his harrowing escape from Poland on the eve of the Second World War; a flight which inadvertently led to his career in virology. A subsequent posting will recount the now discredited, although sensational at the time, accusation that Koprowski’s polio vaccine gave rise to the HIV/AIDS epidemic.

Koprowski was born and grew up in Warsaw, where he earned a medical degree from Warsaw University in 1939. He also was an accomplished pianist, having studied piano from the age of 12 at the prestigious Warsaw Conservatory, where Chopin is said to have studied. Koprowski eventually earned a music degree from the Conservatory. He recalled, “…the first year I was the youngest and voted second best in the class (3).”

koprowski

Hilary Koprowski in Warsaw (2007)

In 1938, while Koprowski was in medical school, he married classmate Irena Grasberg who, in later years, would wonder how they had found the time for their courtship. Each had to contend with a demanding medical school program, while Hilary’s piano studies at the Conservatory was a full time program in itself (3). Irena recalled a day before both of them had an anatomy exam, and Hilary had an important recital. Hilary practiced a recital piece, while simultaneously studying a chart on the music rack showing the bones of the hand; all the while as Irena read anatomy to him.

Koprowski eventually chose a career in medicine, rather than one in music. As he explained: “…the top of the music pyramid is much narrower than that of medicine, where there is more space for successful scientists (3).” Koprowski rated himself only fourth best in his class at the Warsaw Conservatory, and he needed to excel. Yet he may have underrated himself. His piano professor at the Conservatory was “greatly disappointed” when he chose to enter medicine (3). [After the 1944 Warsaw uprising, Koprowski’s piano professor was arrested and beaten to death by German soldiers (see below and 3).] In any case, Koprowski continued to play the piano, and he even did some composing in his later years.

Germany invaded Poland in September 1939, setting off the Second World War. As German bombs were falling on Warsaw, Koprowski answered the call for Polish men to go east, where Polish forces were organizing to resist the Germans. Irena, now pregnant, and Hilary’s mother went with him, while his father chose to remain behind. They made their way in a horse-drawn hay wagon, traveling at night to avoid German planes that were strafing the roads during the day. After a week or so on the road, they encountered refugees moving in the opposite direction. Those refugees told them that Russia had signed a pact with Germany and was now invading Poland from the east (Aside 1). So the three Koprowskis joined the flood of refugees moving to the east. When they arrived back in Warsaw, they found the city in ruins. Many of their friends and neighbors had been killed or were seriously wounded, and the city was occupied by German soldiers.

[Aside 1: The German–Soviet Non-aggression Pact was signed in Moscow in August 1939, as a guarantee of non-belligerence between Nazi Germany and the communist Soviet Union. Hitler broke the pact in June 1941 when Germany attacked Soviet positions in eastern Poland. Hitler had no intention of keeping to the pact. However, it temporarily enabled him to avoid having to fight a war on two fronts—against Britain and France in the west and the Soviet Union in the east.]

Once Germany had conquered Poland, German and Polish Jews began to be sent to concentration camps set up in Poland. The Koprowskis, who were Jewish (Salk and Sabin too were descendants of eastern European Jews), quickly made plans to leave Poland. Their first destination was to be Rome. Hilary’s father went there first to arrange living conditions for the family. To facilitate the escape of Hilary’s father from Poland, Hilary and Irena wrapped him in bandages, hoping that the authorities might gladly believe they were letting a very frail individual depart from the country.

Hilary, Irena, and Hilary’s mother then traveled by train from Warsaw to Rome. It was a harrowing trip. Irena was pregnant, and the Gestapo was roaming the trains. They feared that they might have been arrested at any time.

In Rome, the Koprowski family’s main concern was the safety of Irena and her unborn baby. Since Irena had an aunt in Paris, who would know of a good doctor there, the family thought that Paris would be a safe place for the baby to be born. Thus, Irena left for Paris, accompanied by Hilary’s father. She gave birth to Claude five days after arriving there.

Hilary did not go with Irena to France. If he had done so, he would have been impressed immediately into the Polish Army that was forming there to fight the Germans. Yet he knew that he would eventually have to leave Rome. Italy, under Mussolini’s leadership, was poised to enter the Second World War, as an Axis partner of Hitler’s Germany.

After Claude was born, Irena worked as a physician at a psychiatric hospital in Villejuif, just outside of Paris. She was the sole internist there for eight hundred patients. She kept Claude at the hospital, in a locked room, which she would slip to away every three hours to nurse him.

Back in Rome, Hilary continued to play the piano. In fact, he auditioned for, and was accepted by Rome’s L’Accademia di Santa Cecilia, which awarded him a second degree in music. Importantly, his skill at the keyboard enabled him to get visas for himself and his mother to enter Brazil, which the family hoped would be a safe haven. The best students from L’Accademia di Santa Cecilia were often in demand to play for events at the Brazilian embassy in Rome. Thus, on several occasions, Hilary played the piano at the embassy. Brazil’s consul general admired Hilary’s pianism and was pleased to arrange Brazilian entry visas for Hilary and his mother. See Aside 2.

[Aside 2: The day after Hilary arrived in Rome, he volunteered to serve as a medical examiner for a Polish draft board that was set up in the Polish embassy. The draft board’s activity at the embassy—recruiting Poles for the Polish Army—violated diplomatic protocol. In addition, Italy would soon be Germany’s Axis partner in the War. Moreover, Brazil, though neutral in the War, favored the Axis.]

Hilary and his mother had been making plans to leave Italy. Their destination was to be Spain, where they hoped they might unite with Irena, Claude, and Hilary’s father.  From Spain, the family might then go to Portugal, where they could get a boat to Brazil. But, on the very day that Hilary and his mother were to leave Italy, Mussolini issued a proclamation banning any male of military age from leaving the country. So it happened that Hilary’s escape from Italy was blocked at the boat registration. However, his mother rose to the occasion, crying and pleading with the boat registration official that she was sick, that Hilary was her sole means of support, and that she could not go on without him. “The man looked at his watch and said he must go to lunch. He looked at us and said, ‘If the boat leaves before I return, that’s my bad luck (3).’” So, Hilary and his mother boarded the boat, which left before the official returned. [Hilary’s mother was a well-educated woman, and a dentist by profession.]

In Spain, Hilary and his mother stayed at a hotel in Barcelona. Despite the wartime conditions, they were able to communicate, if only sporadically, with Irena and Hilary’s father, who were still in France. Then, after Germany invaded France in 1940, Irena, Claude, and Hilary’s father reunited with Hilary and his mother in Barcelona. [The escape of Irena, Claude, and Hilary’s father from France was far more harrowing than the escape of Hilary and his mother from Italy (See 3 for details).]

The family now needed to get to Portugal, where they could then get a boat to Brazil. Irena had already obtained Portuguese visas for herself and for Claude. But Hilary and his mother only had visas for Brazil. Hilary’s applications for visas at the Portuguese embassy were repeatedly denied, until a fellow Pole at Hilary’s Barcelona hotel advised him of the obligatory bribe that must accompany visa applications. The advice was right-on, and the family (minus Hilary’s father, who chose to go to England) sailed for Brazil without further incident.

In Brazil, Irena found work in Rio de Janeiro as a nurse. But she soon managed to secure a position as a pathologist at the largest hospital in the city. Hilary, on the other hand, could not find a job in medicine and, so, he turned to teaching piano. After six months of teaching unenthusiastic piano students, Hilary by chance recognized a man on the street in Rio who happened to be a former schoolmate from Warsaw. The man also happened to be working at the Rockefeller Foundation’s outpost in Rio. He told Hilary that the Foundation was looking for people, and he also told Hilary who he should contact there. Hilary interviewed at the Foundation the next day, and was told to report for work the day after that.

The Foundation assigned Hilary to research how well, and for how long the attenuated yellow fever vaccine—developed by Nobel laureate Max Theiler in 1935 (4) —might protect against yellow fever. The disease was endemic in Brazil, and it was actually the Rockefeller Foundation’s first priority.

Hilary’s supervisor at the Foundation was Edwin Lennette; a staff member of the International Health Division of the Rockefeller Foundation, assigned to its Brazilian outpost, specifically because of his interest in yellow fever. In 1944, Lennette would be reassigned to the Rockefeller Foundation laboratory in Berkeley, California, where he would establish the first diagnostic virology laboratory in the United States. Indeed, Lennette is known as one of the founders of diagnostic virology. But, in Brazil, he introduced Hilary Koprowski to virology.

Hilary’s apprenticeship under Lennette was going very well. It would result in nine papers—published between 1944 and 1946— that Hilary would co-author with Lennette. Moreover, Lennette was interested in other viruses, in addition to yellow fever. Thus, their co-authored papers included studies of Venezuelan equine encephalitis virus, Japanese encephalitis virus, St. Louis encephalitis virus, and West Nile virus, as well as yellow fever.

Most importantly, Koprowski’s work under Lennette introduced him to Max Theiler’s methods and approach to viral attenuation. In brief, Theiler found that propagating yellow fever virus in an unnatural host—chick embryos—caused the virus to adapt to that host, thereby reducing its capacity to cause disease in humans.  Koprowski would later acknowledge that Theiler provided him with a “most encouraging model” for attenuating poliovirus. [Koprowski attenuated poliovirus by propagating it first in mice and then in rats. Recall that Sabin developed his live polio vaccine from attenuated poliovirus that he received from Koprowski (1).] See Asides 3 and 4.

[Aside 3: The rabies vaccine, which Louis Pasteur developed in 1885, is often referred to as the first attenuated virus vaccine. Nevertheless, while Pasteur did passage his vaccine virus in rabbit spinal cords, the virus may have been killed when the spinal cords were later dried for up to fourteen days. Also, in Pasteur’s day, nothing was known about immunity or mutation, and viruses had not yet been identified as microbes distinct from bacteria. The yellow fever vaccine developed by Max Theiler at the Rockefeller Institute (now University) in New York may have been the first deliberately attenuated viral vaccine.]

[Aside 4: Koprowski and Lennette were among the first researchers to observe that infection by one virus (yellow fever, in this instance) might inhibit the growth of another unrelated virus (West Nile virus, in this instance). That is, they had inadvertently detected what later would be known as interferon. Yet while they looked for an anti-viral substance in their tissue culture media, and while their results suggest that it actually was there, they stated in their summary that nonspecific anti-viral factors were not present (5). Koprowski and Lennette collaborated again in the 1970s; this time to investigate subacute sclerosing panencephalitis, a rare late complication of measles infection that results in neurodegeneration.]

Hilary continued to give piano recitals in Brazil, regretting only that he did not have time to practice the piano as much as he would have liked. Nonetheless, his piano playing expanded his circle of friends to include musicians, artists and writers, in addition to his fellow scientists. Moreover, Irena was satisfied with her medical practice, and with the many friends and rich social life that she and Hilary had in Brazil.

Earlier, in 1940, while Hilary was still in Rome, and expecting that the family would soon have to leave Europe, he believed that the United States would likely be the best destination for them. Thus, he applied to the United States for visas. He had nearly forgotten those applications when, in 1944, their numbers came up.

The Koprowski family now faced somewhat of a dilemma. It was happily settled in Brazil, and had no prospects in the United States. On the other hand, the Rockefeller Foundation’s yellow fever project was drawing to a close, and the Foundation was planning to leave Rio. Importantly, coming to America was now a “dream come true (3)”.  So, in December 1944, the Koprowskis boarded an aging steamer in Brazil, and sailed under wartime blackout conditions, through German submarine-infested waters, for New York City.

During Hilary’s his first days in America, he used the Rockefeller Institute library in Manhattan to work on manuscripts reporting his research in Brazil. During one of his visits to the Rockefeller, he happened to meet Peter Olitzky (Aside 5), an early polio researcher there, who arranged for Hilary to meet Harold Cox, the director of the virology department at Lederle Laboratories, in Pearl River, New York.  Hilary interviewed with Cox, who offered him a research position at Lederle, which Hilary accepted. Meanwhile, Irena was appointed an assistant pathologist at Cornell Medical College in Manhattan.

[Aside 5: In 1936, Olitzky and Sabin collaborated on a study at the Rockefeller Institute, which, although carefully done, wrongly concluded that poliovirus could attack nerve cells only; a result that did not bode well for the development of an attenuated polio vaccine.]

At Lederle, Hilary began the experiments that led to the world’s first successful polio vaccine. In 1950 he tested the live vaccine in eighteen mentally disabled children at Letchworth Village (1). None of these children had antibodies against poliovirus before he vaccinated them, but each of them was producing poliovirus antibodies after receiving the vaccine. Importantly, none of the children suffered ill effects. What’s more, Koprowski did not initiate the test. Rather, a Letchworth Village physician, fearing an outbreak of polio at the facility, came to Koprowski’s office at Lederle, requesting that Koprowski vaccinate the Letchworth children (1).

References:

   

  1. Vaccine Research Using Children, Posted on the blog July 7, 2016.
  2. Jonas Salk and Albert Sabin: One of the Great Rivalries of Medical Science, Posed on the blog March 27, 2014.
  3. Roger Vaughan, Listen to the Music: The Life of Hilary Koprowski. Springer-Verlag, 2000.
  4. The Struggle Against Yellow Fever: Featuring Walter Reed and Max Theiler, Posted on the blog May 13, 4014.
  5. Lennette EH, Koprowski H., 1946. Interference between viruses in tissue culture, Journal of Experimental Medicine, 83:195–219.

 

 

 

 

 

“The Upright Thinkers”

The Upright Thinkers by Leonard Mlodinow—former professor of Physics at Caltech and author of several other best selling books on science—tells his version of “the human journey from living in trees to understanding the cosmos.” The story is epochal. We begin by noting several of Mlodinow’s general themes.

upright thinkers

Mlodinow asserts that our odyssey of discovery has been driven by our inborn and virtually insatiable curiosity; our propensity to ask “why?” “Human children all around the world ask their first questions at an early age, while they are still babbling and don’t yet speak grammatical language…Chimpanzees and bonobos, on the other hand, can learn to use rudimentary signing to communicate with their trainers, and even answer questions, but they never ask them. They are physically powerful, but they are not thinkers.”

We also are reminded that our astonishing progress was facilitated by a unique characteristic of our species—we add to knowledge already in existence. Recall the famous quote of Isaac Newton, “”If I have seen further than others, it is by standing upon the shoulders of giants.”

Related to the above, there is archaeological evidence that schools existed as early as 2,500 B.C. “…the idea that society should create a profession devoted to passing on knowledge, and that students should spend years acquiring it, was something entirely new—an epiphany for our species.”

Another of Mlodinow’s themes is that the major players in our quest to understand the cosmos (e.g., Newton, Mendeleev, Darwin, Einstein, Bohr, and Heisenberg) were not merely brilliant. They were also stubbornly persistent individuals. Contrary to popular belief, the groundbreaking discoveries they made did not result from sudden “aha moments” but, instead, came about only after years of dogged hard work. There was no apocryphal apple that serendipitously landed on Newton’s head.

Mlodinow also reminds us that scientists, as well as laypeople, do not easily to let go of the conventional beliefs of their day, even when faced with strong evidence to the contrary. Consequently, new scientific paradigms, even when supported by incontrovertible evidence, are often initially rejected by the establishment. And since the revolutionary breakthroughs that Mlodinow highlights in his tale indeed challenged the established wisdom of their times, the scientists who put them forward had to posses more than a little courage and even audacity to complement their doggedness. [Howard Temin provides a recent example of a virologist who persevered in the face of scorn and ridicule from his colleagues. See Howard Temin: “In From the Cold, posted on the blog December 16, 2013.]

Mlidinow allocates several pages to the origin and acceptance of the concept of universally applicable natural laws. The idea of natural laws already existed in ancient Greece. However, Greek natural laws were each specific to a particular situation. Our modern concept of universally applicable natural law came into being only in the early seventeenth century, as prompted by the discoveries of Kepler, Newton, and their contemporaries (see below).

Why might it have taken mankind so long to recognize that nature acts according to certain regularities? The answer may lie in the fact that when primitive humans were faced with seemingly inexplicable droughts, floods, plagues, earthquakes, and so forth, it was difficult for them to view the world as anything but chaotic. Remarkably, even today there still are those who reject the idea of a universe ruled by natural laws. [Consider this. Mlodinow relates that Einstein was astonished by the fact that nature has order. Einstein wrote: “one should expect a chaotic world, which cannot be grasped by the mind in any way… the most incomprehensible thing about the universe is that it is comprehensible.”]

Returning to the theme of our difficulty transitioning from judging the truth of a statement according to how well it fits convention or religious belief, to how well it is supported by empirical evidence, note that for nearly two millennia scientific progress was impeded by the conventions of ancient Greek science. Contrary to popular belief, the Greeks did not invent the scientific method (2). Nor were their theories developed with the intent of experimental verification. Aristotle’s science held that nature did what pure logic suggested it should do. For example, Aristotle said that heavier objects fall faster than lighter objects, because it is their purpose to do so. Neither Aristotle nor his contemporaries actually looked to see if heavier objects indeed fall faster than lighter ones. In fact, the first individual known to have actually tested this premise was Galileo (1564-1642). Only afterwards did observation and experimentation become the basis for western science.

Despite the fact that Aristotle’s non-quantitative search for purpose impeded scientific progress for nearly two thousand years, Mlodinow credits him with applying reason in the pursuit of understanding and, also, for the idea that nature acts according to certain regularities. Mlodinow also notes that Aristotle was hamstrung by the technology of his day. In particular, since Aristotle did not have a stopwatch, concepts such as velocity and acceleration—keystones of Newtonian physics—may have been beyond his reach. But, “More important was the fact that Aristotle was, like everyone else, simply not interested in quantitative description.”

Notwithstanding the above, why did the leap from Aristotelian physics to the breakthroughs of Galileo and Newton take 2,000 years? According to Mlodinow, the conquest of Greece by Rome was a key reason. The Romans were superb engineers, but they had little interest in the pursuit of knowledge for its own sake. Thus, the Roman conquest of the Greeks resulted in the fading out of the Greek scientific heritage from Western culture.

At the end of the eleventh century, a Benedictine monk, Constantinus Africanus, translated ancient Greek medical texts (preserved for centuries by Muslim court scholars) from Arabic to Latin. This was a first step in the revival of the Greek scientific heritage in Europe. Moreover, it was a step towards the eventual resumption of Western science (see Aside 1). Additionally, the development of European universities, such as Oxford (by 1250), facilitated scientific progress in the West, since—then as now—universities are a place that brings people together, where they might interact with and stimulate one another. [Most scientific progress still emanates from universities.] The emergence of moveable-type printing at around 1450 was another key development, since it enabled the widespread dissemination of new ideas.

[Aside 1: Intellectual progress in the Islamic world and in China often surpassed that in Europe during the Middle Ages. Why then did modern science not emerge in the Islamic world, or in China, instead of in Europe? For an answer, I turn briefly to Why the West Rules—For Now by Ian Morris (3). Morris tells us that the resurgence of science in Western Europe was largely driven by Europe’s “new frontier” across the oceans, and the need it created for the precise measurement of time and space. Moreover, “…by the point that two-handed clocks had become the norm Europeans would have to have been positively obtuse not to wonder whether nature itself was not a mechanism.” Additionally, the industrial revolution in the West, which was largely driven by the Atlantic economy, stimulated further mechanical invention and scientific development.]

Galileo was one of the most influential scientists who ever lived and a key figure in the resurgence of European science. One reason for his fame was his experiment at the Leaning Tower of Pisa, which showed that light objects fall as rapidly as heavy ones. Yet while he was disenchanted by the lack of experimentation in Aristotelian physics, he did not invent experimental physics per se. However, his quantitative approach to experimentation was indeed revolutionary. Moreover, “when he got a result that surprised him or went against conventional thinking, he didn’t reject it—he questioned convention and his own thinking.”

One of Galileo’s most insightful and important contentions was that objects in uniform motion tend to remain in that state of motion. That is, an object does not require the continuous application of a force to remain in motion; an assertion that was contrary to the prevailing Aristotelian view that objects require a continuing reason for their motion. If Galileo’s assertion sounds oddly familiar, it is because Newton later adapted it as his first law of motion. [“A few pages after stating the law, Newton adds that it was Galileo who discovered it—a rare instance of Newton giving credit to someone else.”]

Galileo is also famous for his conflict with the Catholic Church over his claim that the Earth is not at the center of the universe. But the idea of a heliocentric (i.e., sun-centered) universe did not originate with Galileo. In fact, it existed as early as the third century B.C. in Greece, and a “modern” European version can be attributed to Copernicus (1473-1543). But Galileo was the first to offer irrefutable proof that the Earth is not at the center of the universes. What’s more, Galileo made his case compelling only after he perfected the telescope, which enabled him to achieve unprecedented levels of power..

Isaac Newton was born in 1642; the year that Galileo died. He is commonly said to have invented the calculus, and to have discovered his laws of motion and universal gravitation, all in the single year, 1666. The last discovery supposedly followed his serendipitous encounter with a falling apple. The reality was a bit different. First, the calculus was concurrently and independently invented by Leibnitz. Second, Newton labored continuously for a period of three years—1664 through 1666—in order to discover his laws of motion. Yet even after accomplishing that feat, Newton was still not a Newtonian. “He still thought of uniform motion as arising from something internal to the body, and by the term ‘gravity’ he meant some inherent property arising from the material an object is made of , rather than an external force exerted by the earth.”

After discovering his laws of universal motion, Newton spent additional years acquiring information, largely compiled by others, regarding planetary orbits. Kepler’s finding—that planetary orbits are ellipses, with the sun at one of the foci—would be especially significant, as follows.

Edmond Halley (the astronomer who computed the orbit of the comet bearing his name), Robert Hooke (the discoverer of cells and perhaps the greatest experimentalist of the seventeenth century), and Christopher Wren (best known as an architect, but also an accomplished astronomer) gleaned from Kepler’s data a premise of singular importance; that the pulling force of the sun diminishes in proportion to the square of the planet’s distance from it. Yet Halley, Hooke, and Wren were unable to prove their conjecture.

Halley, happening to be in Cambridge, took the opportunity to visit Newton. During his visit with Newton, Halley informed his host of the conjecture concerning the pulling force of the sun. Imagine Halley’s surprise when Newton claimed that he had already discovered the premise and, indeed, had already proven it. Newton then set about looking for his proof. But when he found it, he discovered that it was in error. He then set about reworking his proof and, in so doing, he confirmed that Kepler’s planetary orbits indeed are explained by an inverse square law of attraction.

Newton’s proof of the inverse square law of gravitational attraction was followed by more hard work that resulted in “what is perhaps the most significant intellectual discovery that had ever been made”—Newton’s universal theory of motion, which showed that free fall and orbital motion are instances of the same laws of force and motion. Newton set down his laws of motion, and his law of universal gravitation, in his famous Principia; three books published in 1687, which are regarded as the foundation of classical mechanics and, thus, as one of the most important works in the history of science. Halley personally paid the cost of publishing the Principia.

Newton died in 1726. “Newton’s life and Galileo’s had together spanned more than 160 years, and together they witnessed—and in most respects accounted for—most of what is called the scientific revolution.”

A revolution in chemistry was occurring concurrent with the ones in physics and astronomy. The key breakthrough in chemistry would be the discovery that some substances—the elements—are fundamental, and that all else is made from them. Actually, the concept of elements dates back to Aristotle and the ancient Greeks. However, Aristotle’s chemistry had but four “elements”—earth, air, fire, and water.

The experimental results of Robert Boyle (1627-1691) were the first to free chemistry from Aristotelian convention. Mlodinow relates how in 1642, the 15-year-old Boyle was taken with science after reading Galileo’s book on the Copernican system. Afterwards, the adult Boyle (incidentally assisted by Robert Hooke) investigated respiration and combustion. His findings led him to conclude that air is not an element but, instead, is made up of different substances. Moreover, Boyle’s quantitative approach set in place a new convention in chemistry of careful experimental analysis.

Boyle’s experiments were followed by those of Joseph Priestly (1733-1804) and of Antoine Lavoisier (1743-1794). The relationship between these two men makes for an interesting tale, one that is too long to review here. But, together, their researches showed that respiration and combustion removed something from the air. Priestly may have discovered it first, but Lavoisier gave it its name, oxygen. Lavoisier went on to reveal one of chemistry’s major principles—the conservation of mass. That is, the total mass of the products produced in a chemical reaction must be the same as the combined mass of the initial reactants.

Lavoisier had been a tax collector in Paris in the days preceding the French Revolution. His day job provided financial support for his experiments, but it did not endear him to the revolutionaries who overthrew the French monarchy. He was arrested in 1793 during the Reign of Terror and sentenced to death. The presiding judge is said to have told him, “The Republic has no need of scientists.” “By the time of his execution, Lavoisier had identified thirty-three known substances as elements. He was correct about all but ten.”

The next important advancements would involve the nature of atoms. Although Lavoisier identified the elements as the reactants in chemical processes, he chose not to think in terms of atoms. His reason was simply that he did not know of any way by which something as tiny as an atom could be observed or experimented on. John Dalton (1766-1844) took the first step towards solving that problem when he discovered how to determine atomic weights by applying Lavoisier’s law of conservation of mass. [Mlodinow details Dalton’s approach.]

Dmitry Mendeleev (1834-1907) made a crucial breakthrough that would lead to an understanding of the relationship between the weight of an atom and its chemical properties. [The relationship of course involves atomic numbers, rather than atomic weights. Please be patient.] How that development came to pass was one of my favorite anecdotes in Mlodinow’s book. It was as follows. In 1866, while Mendeleev was a chemistry professor in St. Petersburg, he could not find a first-rate, up-to-date chemistry book, written in Russian, that he might use in his teaching. So, he decided to write his own. Mendeleev’s book was a labor of love that he worked on for years. Early on, he wrestled with the question of how to organize the book. His solution was to arrange the elements and their compounds into groups, as defined by their properties. Then, after much arranging and rearranging of the elements, he discovered a pattern that we know today as the “periodic table;” a discovery of singular importance that Mlodinow calls “chemistry’s version of Newton’s laws.”

Much important work remained to be done. Because there were as yet undiscovered elements, there were gaps in the Mendeleev’s table. Moreover, some of the assigned atomic weights were wrong and, crucially important, the chemical properties of an element are determined by the as yet undiscovered atomic numbers, rather than by atomic weights. Notwithstanding that, to Mendeleev’s credit, he accurately predicted the existence and chemical properties of the elements which corresponded to the gaps in his table.

The twentieth-century revolution in physics led to profound insights into the nature of space and time, and to a deeper “understanding” of the atom. Mlodinow tells that story only after he reviews several key breakthroughs in biology. Keeping with his format, he notes the early influence of Aristotelian convention on biology. Two Aristotelian beliefs were especially important. One was the belief that a divine intelligence designed all living beings. The other was the belief in spontaneous generation.

Readers of the blog are likely familiar with Louis Pasteur’s late nineteenth-century experiments, which laid spontaneous generation to rest once and for all (4). Many readers may also know that Francesco Redi experimentally challenged spontaneous generation more than two centuries earlier. In 1668, Redi’s microscopic observations of minute organisms showed that they are much more complex than had been imagined. In particular, these organisms had reproductive organs, which called into question one of Aristotle’s arguments for spontaneous generation; that lower organisms are too simple to reproduce.

The notion, that a divine intelligence was necessary to design all living beings, was a foundation stone of nineteenth-century thinking. Under that circumstance, Charles Darwin (1809-1882) gave the world a scientific theory—evolution by natural selection— that explained how species came to have their particular characteristics. Darwin’s theory directly challenged the biblical account of creation, which still has a very significant number of adherents. Thus, it is all the more remarkable that his grave occupies hallowed ground under Westminster Abbey.

Legend has it that Darwin had an “aha moment” while observing the beaks of finches on different islands of the Galapagos. The reality is that Darwin only gradually came to believe that species are not unchanging forms designed by God but, instead, evolved over time. And Darwin devoted many more years to discovering the mechanism behind evolution—natural selection. Moreover, knowing that his findings would expose him to ridicule and attack, he spent more years amassing incontrovertible evidence in support of his theory.

Darwin did not know of genes and mutations. Consequently, he was unaware of how genetic variability might provide the raw material for adaptation. His contemporary, Gregor Mendel (1822-1884), made the breakthrough in genetics. Mendel, carried out his experiments while a monk at a monastery in what is now the Czech Republic, perhaps explaining why Darwin never knew of his work.

One way or another, serendipity is usually a factor in all great scientific discoveries. Apropos the theory of evolution, Darwin likely would have remained an unknown English churchman were it not for the unlikely and unexpected letter inviting him, at twenty-two years of age, to sail around the world as a naturalist on the Beagle. The position on the Beagle was beforehand offered to a number of others, none of whom were willing to spend two years at sea.

Mlodinow devotes the last 100 or so pages of his book to the twentieth-century revolution in physics. Considering the stunning discoveries that were about to unfold, it is more than a bit ironic that the prevailing belief at the start of the century was that everything in physics was already known and that nothing else remained to be done.

Key individuals who fill Mlodinow’s final pages include Max Planck (see Aside 2), Albert Einstein (see Aside 3), Ernest Rutherford (see Aside 4), Niels Bohr (see Aside 5), and Werner Heisenberg and Erwin Schrodinger (see Aside 6).

[Aside 2: Max Planck was a German physicist who deduced the relationship between the frequency of radiation and its energy. Moreover, he proposed that electromagnetic energy could only take on discrete values, or quanta. In so doing, he originated quantum theory.

Mlodinow tells the following quip: “Since my name is so hard to spell and pronounce, when I make a restaurant reservation, I often do it under the name Max Planck. It’s very rare that the name is recognized, but one time when it was, I was asked if I was related to the “guy who invented quantum theory.” I said, “I am that man.” The maitre d’, in his early twenties didn’t believe me. He said I was too young. “Quantum theory was invented around 1960,” he said. “It was during World War II, as part of the Manhattan Project.”]

[Aside 3: In the single year 1905, while Einstein was employed as a third-class clerk at the Swiss patent office in Zurich, he published three singularly important, ground-breaking papers. The first paper explained Brownian motion, the second the photoelectric effect (in which light impinging on a metal causes it to emit electrons), and the third, his discovery of special relativity. Although each of the three papers dealt with a different topic, astonishingly, each was important enough to merit a Nobel-Prize. And, since Einstein is best known for his theories of relativity—which revolutionized our concepts of space and time—it may surprise some that his Nobel Prize was actually awarded for his explanation of the photoelectric effect. Einstein’s key insight was to treat light as a quantum particle, rather than as a wave. Consequently; his analysis of the photoelectric effect would significantly advance further developments in quantum theory; which Einstein eventually came to abhor (see below). His explanation of Brownian motion provided the most convincing evidence of the day for the existence of atoms. After years more of work, Einstein put forth his theory of general relativity, which incorporated gravity into relativity theory.]

[Aside 4: Rutherford discovered of the structure of the atom, with its positive charge concentrated in the nucleus. Interestingly, this key advancement  began fortuitously, as a “small research project,” for a young undergraduate student named Ernest Marsden; for him “to get his feet wet.”]

[Aside 5: Bohr applied quantum mechanics to the whole atom, asking what it might mean if the atom, like light quanta, could have only certain energies. His premise, that electrons occupy only certain allowable orbits, provided an explanation for why electrons don’t spiral into the atom’s nucleus. And his proposal that the atom’s outer orbits determine its chemical properties, gave new insights into why Mendeleev’s heretofore mysterious periodic table worked.]

[Aside 6: Heisenberg and Schrodinger proposed dissimilar quantum theories, each of which left behind Newton’s conventional description of reality. In Newton’s physics, position and velocity are independently measured quantities, one event causes another, and the world exists independently of our observation of it. In quantum theory, reality is based on probabilities and uncertainties, and reality does not exist independently of our observations. At a scientific conference, when Einstein famously attacked the indeterminacy and probabilistic nature of quantum physics, saying “God does not play dice with the universe,” Bohr famously replied, “Einstein, stop telling God what to do (5).” Yet even Schrodinger eventually turned against quantum theory, offering up his famous fable of the cat that was neither alive nor dead, to point up the seeming absurdity of the theory. Still, quantum theory remains as the most predictive of all scientific theories.]

The Nazis came to power in Germany in 1933. They hated the new physics for being surreal and abstract but, more importantly, because they considered it to be the work of scientists of Jewish heritage (e.g., Einstein, Born, Bohr, Pauli). [Incidentally, the new physics was also condemned in the Soviet Union in the early 1920s; in that instance for not conforming to the principles of Marxist-Leninist ideology. The Soviets similarly banned Mendelian genetics for the same reason.]

Einstein was still living in Germany when the Nazis took control. But, fortunately, he was visiting Cal Tech on the very day in January 1933 when Hitler became Chancellor. He never returned to Germany. His property in Germany was confiscated, his notes on relativity were burned, and a five-thousand-dollar bounty was put on his head.

Heisenberg tried to accommodate himself to the Nazis, but he was nevertheless harassed by them for having worked on “Jewish physics” with Jewish physicists, and for trying to have Max Born (incidentally Max Delbruck’s mentor) exempted from the Nazi non-Aryan work prohibition. Under pressure, Heisenberg disavowed the Jewish physicists and “their” science.

Max Born, with the help of Pauli’s refugee organization, escaped to Cambridge. Schrödinger, an Austrian who had been living in Berlin when Hitler came to power, was an outspoken anti-Nazi. He left Berlin to take a position at Oxford. Bohr’s real-life exploits during the Nazi era are more fascinating than fiction, and are covered in some detail in reference (5).

In 1933, Max Planck met face-to-face with Hitler to dissuade him from carrying out the anti-Jewish policies that were causing top Jewish scientists to leave Germany. The meeting came to nothing, and Planck quietly went on with his work. However, Planck’s youngest son was a member of the failed plot to assassinate Hitler on July 20, 1944. He was arrested by the Gestapo and was executed along with the other conspirators. Earlier, in 1907, when women were nearly entirely barred from receiving advanced education, Planck invited Lisa Meitner (only the second woman to receive a physics doctorate from the University of Vienna) to carry out postdoctoral studies under his guidance (5). Mlodinow includes Meitner among the short list of physicists who he believes deserved, but did not receive the Nobel Prize. See Aside 6. [Reference 6 notes the wartime experiences of Andre Lwoff, Francois Jacob, Jacques Monod, and Elie Wollman. Reference 7 describes a wartime experience of Renato Dulbecco.]

[Aside 7: By 1938, Lisa Meitner’s situation in Nazi Germany had become desperate. So she fled to Holland, aided by Dutch physicists who persuaded their government to admit her on her Austrian passport, which was no longer valid after the Anschluss (5). She next moved to Sweden, where Niels Bohr found for her a laboratory where she could continue her work. While in Sweden, she received a correspondence from her former collaborator in Germany, chemist Otto Hahn, from which she and her nephew Otto Frisch calculated that Hahn had unknowingly witnessed nuclear fission (5). Meitner passed that information on to Niels Bohr, which Bohr took to America and made public at a January 1939 conference at George Washington University. Leading proponents of the new physics immediately realized that a nuclear bomb was now possible. The famous Einstein letter of August 1939, which warned Franklin Roosevelt of that possibility, led to the American Manhattan Project to develop an atomic bomb. German scientists, led by Heisenberg, likewise began work on nuclear energy. In September 1939, Germany invaded Poland and World War II was underway. By September, 1941, Britain was fighting alone against Germany in the west, and the Soviets were reeling under the German onslaught in the East. Those were the circumstances under which Heisenberg attended a German-sponsored conference in Nazi-occupied Copenhagen. Bohr boycotted the conference in protest against the Nazis. However, Heisenberg sought out his former mentor in Copenhagen for a private meeting. While it is known that Bohr and Heisenberg discussed the nuclear weapon issue, the two men were never able to agree on exactly what was said, or even where their conversation actually took place, and to this day their meeting remains shrouded in mystery. Perhaps because Bohr was potentially a huge scientific asset to the Germans, or perhaps because his life was in danger because of his Jewish heritage, the British in 1943 carried out a harrowing rescue mission to smuggle him out of occupied Denmark. Details of the rescue are recounted in reference 5. Bohr then came to America, where he worked on the Manhattan Project and he later became an outspoken arms control advocate. Although it is not entirely clear, there are reasons to believe that Heisenberg may have surreptitiously impeded the German nuclear effort. Bohr and Heisenberg reestablished their relationship after the war, but their shaky friendship was sustained only by their mutual understanding not to revisit their 1941 meeting.]

Mlodinow asserts that “quantum theory was created by a concentration of brain power in Central Europe that surpassed or at least rivaled that of any of the intellectual constellations we’ve encountered in our journey through the ages.” Moreover, “It was a magical time in Europe, with burst after burst of imagination lighting the sky, until the outline of a new realm of nature began to appear.”

A photo in The Upright Thinkers, taken at the famed 1927 Fifth Solvay International Conference on Electrons and Photons, shows Erwin Schrodinger, Wolfgang Pauli, Werner Heisenberg, Paul Dirac, Max Born, Niels Bohr, and Albert Einstein among others; thus bearing out Mlodinow’s contention that it was a very special time in the history of science.

The “golden age of molecular biology” of the 1950s and 1960s is not discussed in The Upright Thinkers. Thus, I feel an urge to proclaim before closing that it too was a very special time in the history of science, when fundamental discoveries were made in biology that were comparable in significance to those made earlier in the century in physics . As a graduate student in the 1960’s I was privileged to experience the thrill of attending, and speaking at the summer conferences at Cold Spring Harbor, which were simultaneously graced by James Watson, Francis Crick, Max Delbruck, Sidney Brenner, Francois Jacob, Jacques Monod, Seymour Benzer, and Norton Zinder (all of whom are discussed elsewhere on the blog), as well as by the likes of Erwin Chargaff, Matthew Meselson, Frank Stahl, Sol Spiegelman, John Beckwith, and so forth.

This piece at last concludes with an item from The Upright Thinkers, which I found to be especially intriguing. Recent DNA analysis shows that around 140,000 years ago, a catastrophic event—possibly related to climate change—caused the entire human population to plummet to a mere several hundred individuals. We truly were an endangered species. “Isaac Newton, Albert Einstein, and everyone else you’ve ever heard of, and the billions of us who live in the world today, are all descendants of those mere hundreds who survived.”

References:

(1) Leonard Mlodinow, The Upright Thinkers, Pantheon Books, 2015.

(2) Thucydides and the Plague of Athens, posted on the blog September 30, 2014.

(3) Ian Morris, Why the West Rules—For Now, Farrar, Straus and Giroux, 2010.

(4) Louis Pasteur: One Step Away from Discovering Viruses, posted on the blog January 7, 2015.

(5) Max Delbruck, Lisa Meitner, Niels Bohr, and the Nazis, posted on the blog November12.

(6) Genealogies and a Selective History of Lysogeny: Featuring Friedrich Loeffler, Emile Roux, Andre Lwoff, Elie Wollman, and Francois Jacob, posted on the blog January 28, 2015.

(7) Renato Dulbecco and the Beginnings of Quantitative Animal Virology, posted on the blog December 3, 2013.

Genealogies and a Selective History of Lysogeny: Featuring Friedrich Loeffler, Emile Roux, Andre Lwoff, Elie Wollman, and Francois Jacob

I am intrigued by the genealogies of our leading scientists, since their mentors too were often preeminent scientists. Earlier postings noted the example of Jonas Salk, who did postgraduate studies under Thomas Francis; one of the great pioneers of medical virology, perhaps best known for developing the first influenza vaccine (1, 2). James Watson, who did his doctoral studies in Salvatore Luria’s laboratory, and Renato Dulbecco, who trained under both Luria and Max Delbruck (3), are other examples. In fact, Watson and Dulbecco shared a lab bench in Luria’s lab. Howard Temin did his doctoral (and postdoctoral studies too) in Dulbecco’s lab (4). And Delbruck, who hugely influenced the new science of molecular biology, did his doctoral studies under Max Born, the 1954 Nobel Laureate in physics. Moreover, Delbruck later served as an assistant to Lisa Meitner (5).

Important research paths were undertaken, and major contributions were made, which resulted from less formal interactions between budding young scientists and top scientists of the day. Howard Temin’s chance encounter with Harry Rubin, while on a mission to Dulbecco’s lab, is a case in point (4).

Our last posting told how Louis Pasteur came within a whisker of adding the discovery of viruses to his list of extraordinary achievements (6). Robert Koch played a part in that story for developing his famous postulates, which provided the standard for demonstrating that a particular microbe causes a particular disease.

The Pasteur article also noted that in 1898 Friedrich Loeffler and Paul Frosch isolated the foot and mouth disease virus; the first virus isolated from animals. However, the piece did not point up that Loeffler had trained under Robert Koch. Also, it did not underscore the special significance of what Loeffler and Frosch achieved. In brief, by the 1890s Dmitry Ivanovsky and Martinus Beijerinck had independently discovered that the agent responsible for tobacco mosaic disease passes through bacterium-proof filters. Nevertheless, neither Ivanovsy nor Beijerinck appreciated the implication of their observation. Ivanovsky believed his filters might be defective, while Beijerinck thought the disease was caused by a “living liquid.” In contrast, Loeffler and Frosch, in addition to isolating the first virus that is pathogenic in animals, also carefully considered all possible explanations for their experimental findings, and then were the first to conclude the existence of a kind of microbe too small to be retained by bacterium-proof filters, and too small to be seen under a microscope, and that will not grow on laboratory culture media. They also correctly predicted that smallpox, cowpox, cattle plague, and measles are similarly caused by a “filterable virus.”

Loeffler made another major discovery, fourteen years earlier, in 1884, when he used his mentor’s postulates to identify the bacterium that causes diphtheria, Corynebacterium diphtheriae. Importantly, Loeffler also discovered that when he injected C. diphtheriae into animals, the microbe did not need to spread to the tissues it damaged. This observation led Loeffler to propose the bacteria were secreting a poison or toxin that spread to the remote sites and caused disease there.

Loeffler’s idea of a toxin was a new concept that subsequently was confirmed by Emile Roux, who had been Louis Pasteur’s assistant (6). Using bacterium-proof filters developed by Charles Chamberland in Pasteur’s lab, Roux showed that injecting animals with sterile filtrates of C. diphtheriae cultures caused death with a pathology characteristic of actual diphtheria. Roux was also a co-founder of the Pasteur Institute, where he was responsible for the production of diphtheria anti-toxin; the first effective diphtheria therapy. See Aside 1.

[Aside 1: Earlier, Roux suggested the approach Pasteur used to generate attenuated rabies virus for the Pasteur rabies vaccine (aging spinal cords from rabbits that succumbed to experimental rabies infections of their spinal cords). Roux later withdrew from the rabies project because of a disagreement with Pasteur over whether the rabies vaccine might be safe for use in humans (6).]

So, Loeffler and Roux trained under Koch and Pasteur, respectively. But why might toxin production by C. diphtheriae interest virologists. Well, in 1951, Victor Freeman at the University of Washington showed that the lethal toxins produced by C. diphtheriae (and by Clostridium botulinum as well) are the products of lysogenic bacteriophage carried by the bacteria. This was shown by the finding that avirulent strains of these bacteria became virulent when infected with phages that could be induced from virulent strains. So, are diphtheria and botulism due to bacteria or to viruses? Our chain of genealogies continues with a selective history of lysogeny.

Almost from the beginning of phage research (bacteriophage were discovered independently by Frederick Twort in Great Britain in 1915 and by Félix d’Hérelle in France in 1917), some seemingly normal bacterial cultures were observed to generate phage. Initially, this phenomenon was thought to be a sign of a smoldering, steady state kind of persistent phage infection. Then, during the 1920s and 1930s, the French bacteriologists, Eugene Wollman and his wife Elizabeth, working together on Bacillus megatherium at the Pasteur Institute, provided evidence that instead of a steady state infection, the phage actually enter into a latent form in their host cells; a form in which they might be harmlessly passed from one cell generation to the next. [Considering the state of knowledge back then, note the insightfulness of Eugene Wollman’s 1928 comment, “the two notions of heredity and infection which seemed so completely distinct and in some ways incompatible, . . . almost merge under certain conditions.”] See Aside 2.

[Aside 2: Since some bacterial strains would, on occasion, spontaneously undergo lysis and release bacteriophage, the cryptic bacteriophage they carried were called “lysogenic.” Thus, it is a bit odd that “lysogeny” eventually came to refer to the temperate relationship between these phages and their host cells.]

In the late 1930s, the Wollmans developed a close friendship with Andre Lwoff, their new colleague at the Pasteur Institute. The Wollmans introduced Lwoff to their ideas about lysogeny, but, as Lwoff confesses, he was not then impressed by bacteriophage (7).

The Nazi occupation of Paris during the Second World War began in 1940. From then on, the Jewish Wollmans were prevented from publishing their research findings. Nevertheless, they continued their research at the Pasteur Institute until 1943, when they were seized by the Nazis and sent to Auschwitz. They never were heard from again. Their friend, Lwoff, grieved their loss and became active in the French resistance, gathering intelligence for the Allies, while also hiding downed American airmen in his apartment.

After the war, Lwoff received several honors from the French government for his efforts against the Nazis. He also returned to his research at the Pasteur Institute, studying the genetics of Moraxella; a bacterial pathogen of the human respiratory tract. Because of his work as a microbial geneticist, he was invited to the 1946 Cold Spring Harbor Symposium, where he met Max Delbruck. And as happened to others, meeting Delbruck resulted in Lwoff being seduced by bacteriophage.

Andre Lwoff
Andre Lwoff

Back in Paris, Lwoff’s passionate interest in phages was heightened further by discussions with Jacques Monod, a friend of Max Delbruck, and Lwoff’s neighbor in the attic of the Pasteur Institute. Although Monod was Lwoff’s junior colleague (in fact, it was Lwoff who first stirred Monod’s interest in microbiology), Lwoff’s conversations with the future Nobel Laureate resulted in Lwoff becoming intensely fascinated by lysogeny, which he began to study in 1949 (7).

Because of Lwoff’s earlier friendship with the Wollmans, he chose to study a lysogenic strain of B. megatarium. And, making use of techniques he learned from Renato Dulbecco during a brief stint at Cal Tech, he was able to follow a single lysogenic bacterium, which enabled him to observe that a bacterium could go through multiple rounds of replication without liberating virus. What’s more, he discovered that the phages are released in a burst when the cell lyses, thereby dispelling the still current notion that phages are liberated continuously by lysogenic bacteria. Furthermore, Lwoff showed that lysogenic bacteria usually do not contain phage particles, since none are detected when the cells are experimentally lysed with lysozyme; confirming the earlier (1937) findings of the Wollmans.

Lwoff went on to show that temperate phage genomes are maintained in a previously unknown integrated state in their host cell, and he gave the integrated phage genomes a name, “prophage.” He also discovered, unexpectedly, that irradiating lysogenic bacteria with ultraviolet light could induce the temperate phages to emerge from their latent state, and then replicate in, and lyse their host cells. And, he discovered that the phages lyse their host bacterial cells by producing enzymes that destroy bacterial cell walls.

Prophage
Prophage

Lwoff’s elucidation of the fundamental nature of lysogeny in bacteria would later provide a paradigm for the DNA tumor viruses, the herpesviruses, the oncogenic retroviruses, and HIV. He was awarded a share of the 1965 Nobel Prize for physiology or medicine for his lysogeny research. He shared the award with his fellow Pasteur Institute scientists, François Jacob and Jacques Monod, who received their awards for their pioneering studies of gene regulation in E. Coli.

A rather intriguing aspect of this story is that Lwoff was joined in his research on lysogeny at the Pasteur Institute by Elie Wollman; the son of Eugene and Elizabeth. Elie, born in 1917, escaped from the Nazis in Paris in 1940 and worked in the French resistance as a physician. In 1946, after the war, he came to the Pasteur Institute, where he took its microbiology course and then became Lwoff’s research assistant. Then, in 1947, Elie too happened to meet Max Delbruck (in Paris in this instance) and was invited to join the Cal Tech phage group, where he spent the next two years. See Aside 3.

Elie Wollman
Elie Wollman

[Aside 3: By the early 1940s, the then young Cal Tech “phage group,” headed by Max Delbruck, was on its way to becoming the World’s great center for phage research (5). However, the American group had little interest in lysogeny, since Delbrück neither believed in it, nor saw its importance. Instead, Delbruck was totally committed to the study of lytic phages. Then, during the late 1940s, Delbruck began to lose interest in molecular biology and looked for new research directions. When he thought of turning his attention to brain function, he asked his group to put together a series of seminars based on papers written by prominent neuroscientists of the day. Elie Wollman was the only member of the Cal Tech group who declined to participate in that endeavor, since he was totally committed to bacteriophage. Moreover, Elie was the one who finally convinced Delbruck that “such a thing as lysogeny does exist (7).”

Elie himself tells us that when he looked into a bibliographical index at Cal Tech, he came across an index card referring to his parent’s 1937 paper, which reported their finding that lysogenic cells contain a non-infectious form of the phage (8). “Delbruck’s comment on the card was “Nonsense.”]

After Eli’s two-year stint with Delbruck in Pasadena, he returned to the Pasteur Institute. Meanwhile, Francois Jacob had come to the Institute in the hope of beginning a research career in genetics under the tutelage of either Lwoff or Monod. Before that, in 1940, Jacob, who also was Jewish, left medical school in occupied France to join Free French Forces in London. He then served as a medical officer in North Africa, where he was wounded, and was later severely wounded at Normandy in August 1944, ending his dream of becoming a surgeon.

Francois Jacob
Francois Jacob

Initially, Jacob was spurned by both Lwoff and Monod, but was finally taken on by Lwoff, who suggested that he, Jacob, start work on “the induction of the prophage.” Jacob confesses he had no idea what that meant, but he accepted the project. Thus it came to pass that Francois Jacob and Elie Wollman established a particularly close and friendly collaboration, in which they turned their attention to the lambda prophage of E. coli. Their initial goal was to clarify the events of bacterial conjugation so that they might then understand the phenomenon whereby a temperate phage carried by a lysogenic bacterium is activated to undergo vegetative replication when that bacterium conjugates with, and transfers its integrated phage genome to a non-lysogenic bacterium.

To accomplish their goal, Wollman and Jacob began with experiments to locate the lambda genome on the chromosome of the lysogenic cell, and to follow its transfer during conjugation into a non-lysogenic recipient cell. A key feature of their experimental approach was conceived by Wollman (8). It was simply to interrupt conjugation between a lysogenic donor (Hfr) cell and a non-lysogenic recipient (F-minus) cell, at various times, by using a kitchen blender to break the mating cells apart. Using the blender to interrupt conjugation, and also using bacterial strains in which the recipient bacteria contained a set of mutations, and plating the mating mixture on selective media, Wollman and Jacob were able to measure the length of time required for each of the corresponding wild-type genes to be transferred from the Hfr donor cells to the F-minus recipient cells. Indeed, the time intervals between the appearances of each wild type gene in the recipient cells directly correlated with the distances between the genes, as independently determined by recombination frequencies. Thus, the interrupted mating approach gave Wollman and Jacob a new means to construct a genetic map of the bacterium, while also enabling them to locate the integrated phage genome on that map. Their experimental approach also allowed Wollman and Jacob to establish that, during conjugation, the donor cell’s genome is transferred linearly to the recipient cell. [The designation “Hfr” was coined by William Hayes because Hfr strains yielded a high frequency of recombinants when crossed with female strains.]

Importantly, Wollman and Jacob’s study of the activation of a lambda prophage when it enters a non-lysogenic F-minus recipient (a phenomenon they called “zygotic induction”), showed that the temperate state of the lambda prophage is maintained by some regulatory factor present in the cytoplasm of a lysogenic bacterium, but which is absent from a non-lysogenic one. It led to the discovery of a “genetic switch” that regulates the activation of the lysogenic bacteriophage, and of a phage-encoded repressor that controls the switch. These findings are among the first examples of gene regulation, and are credited with generating concepts such as the repressor/operator, which were firmed up by Jacob and Monod in their Nobel Prize-winning studies of the E. coli lac operon. See Aside 4.

[Aside 4: At the time of Wollman and Jacob’s interrupted mating experiments, kitchen blenders had not yet made their way to European stores. Eli was aware of these appliances only because of his earlier stint at Cal Tech. He bought a blender for his wife before returning to France, and then “borrowed” it for these experiments.]

Wollman and Jacob went on to demonstrate that the fertility or F factor, which confers maleness on the donor bacteria, can exist either in an integrated or an autonomous state. Indeed, this was the first description of such a genetic element, for which they coined the term “episome;” a term now largely replaced by “plasmid.”

Wollman and Jacob also determined that the E. coli chromosome is actually a closed circle. The background was as follows. Only one F factor is integrated into the chromosome of each Hfr strain, and that integration occurs at random. And, since the integrated F factor is the origin of the gene transfer process from the Hfr cell to the F-minus cell, interrupted mating experiments with different Hfr strains gave rise to maps with different times of entry for each gene. However, when these time-of-entry maps were taken together, their overlapping regions gave rise to a consistent circular map. The discovery of the circular E. coli chromosome was most intriguing, because all previously known genetic maps were linear. See Aside 5.

[Aside 5: The bacterial strain used by Wollman and Jacob in their study of zygotic induction was, in fact, the original laboratory strain of E. coli (i.e. E. coli K12) that was isolated in1922 from a patient with an intestinal disorder. In 1951, Esther Lederberg discovered that K12 is lysogenic. The discovery happened when she accidentally isolated non-lysogenic or “cured” derivatives of E. coli K12 that could be infected by samples of culture fluid from the parental K12 strain, which sporadically produced low levels of phage. Esther gave the lysogenic phage its name, lambda.

Esther was the wife of Joshua Lederberg, who received a Nobel Prize in 1958 for discovering sexual conjugation in bacteria, and the genetic recombination that might then ensue. Prior to Lederberg’s discoveries, genetic exchange and recombination were not believed to occur in bacteria. Lederberg’s Nobel award was shared with George Beadle and Edward Tatum (the latter was Lederberg’s postdoctoral mentor) for their work in genetics.

Joshua Lederberg, working with Norton Zinder (9), also discovered transduction, whereby a bacterial gene can be transferred from one bacterium to another by means of a bacteriophage vector. And, working together with Esther, Joshua discovered specialized transduction, whereby lambda phage transduces only those bacterial gene sequences in the vicinity of its integration site on its host chromosome. Esther and Joshua also worked together to develop the technique of replica plating, which enabled the selection of bacterial mutants from among hundreds of bacterial colonies on a plate and, more importantly perhaps, to provide direct proof of the spontaneous origin of mutants that have a selective advantage.]

In 1954 Elie Wollman was appointed a laboratory head in his own right at the Pasteur Institute. He retired from research in 1966 to become vice-director of the Institute, which he then rescued from a severe financial crisis. He continued to serve in that role for the next 20 years, while garnering numerous prestigious awards for his research and service.

Francois Jacob earned his doctorate in 1954 for his lysogeny studies. Then, realizing that he and Jacques Monod, his senior neighbor in the Pasteur Institute attic, were actually studying the same phenomenon, gene repression, he entered into a hugely productive collaboration with Monod that led to the elucidation of the genetic switch that regulates beta-galactosidase synthesis in E. coli (9). Their collaboration established the concepts of regulator genes, operons, and messenger RNA, for which they shared in the 1965 Nobel Prize for physiology or medicine, as noted above. See Asides 6 and 7.

Jacques Monod
Jacques Monod

[Aside 6: One of Jacob and Monod’s first experiments was the famous 1957 PaJaMa experiment, carried out in collaboration with Arthur Pardee, who was then on sabbatical at the Pasteur Institute. In brief (for aficionados), a Lac-positive, Hfr strain was grown in an inducer-free media, and then mated, still in an inducer-free media, with a Lac-minus, F-minus strain. (Note that the deletion in the Lac-minus, F-minus strain included the LacI gene, which encodes the yet to be discovered lac repressor.) As expected, in the absence of inducer, no beta-galactosidase is detected initially. But, after the donor DNA sequence, which bears the normal Lac genes (including LacI), is transferred to the Lac-minus recipient, it initially finds no repressor in the recipient cell and begins to synthesize beta-galactosidase. Then, as the donor cell’s lac repressor gene begins to be expressed in the recipient cell, in the inducer-free media, expression of the donor cell’s beta-galactosidase gene ceases. The PaJaMa experiment thus showed that the genetic regulation of enzymatic induction depends on a previously unknown regulatory molecule, the repressor.

Notice the similarity between the rationale for the PaJaMa experiment and that of the earlier Wollman and Jacob experiment on zygotic induction. In each instance, a process regulated by a repressor is suddenly in the repressor-free environment of a recipient cell.]

[Aside 7: In June of 1960, Francois Jacob, Matt Meslson, and Sidney Brenner came together in Max Delbruck’s Cal Tech lab to carry out an experiment that confirmed the existence of messenger RNA. The key to the experiment was their ability to distinguish ribosomes present in the cell before infection from ribosomes that might have been made after infection. They cleverly did that by incorporating heavy isotopes into ribosomes before infection, so that they might be separated in a density gradient from ribosome made after infection. Then, they showed that RNA produced by T2 phage in E. Coli associates with ribosomes that were synthesized by the cell entirely before infection. Furthermore, the new phage-specific RNA directs the synthesis of phage-specific proteins on those “old” ribosomes. I vote for this experiment as the most elegant in the entire history of molecular biology (11).]

Incidentally, during the Nazi occupation of Paris, Monod too was active in the French Resistance, eventually becoming chief of staff of the French Forces of the Interior. In that capacity, he helped to prepare for the Allied landings in Normandy. Monod and Jacob each received France’s highest honors for their wartime service.See Aside 7.

[Aside 7: I am singularly intrigued by the experiences of Andre Lwoff, Elie Wollman, Francois Jacob, and Jacques Monod during the Second World War. References 3 and 5 recount the wartime experiences of Renato Dulbecco and of Max Delbruck, and of other great scientists of the time. Other posts on the blog give accounts of virologists courageously placing themselves in harm’s way under different circumstances. Examples include pieces featuring Ciro de Quadros, Carlo Urbani, Peter Piot, and Walter Reed.]

References:

(1) Jonas Salk and Albert Sabin: One of the Great Rivalries of Medical Science, Posted on the blog March 27, 2014.

(2) Ernest Goodpasture and the Egg in the Flu Vaccine, Posted on the blog November 25, 2014.

(3) Renato Dulbecco and the Beginnings of Quantitative Animal Virology, Posted on the blog, December 4, 2013.

(4) Howard Temin: “In from the Cold,” Posted on the blog December 16, 2013
(5) Max Delbruck, Lisa Meitner, Niels Bohr, and the Nazis, Posted on the blog November 12, 2013.

(6) Louis Pasteur: One Step Away from Discovering Viruses, Posted on the blog January 7, 2015.

(7) Lwoff, Andre, The Prophage and I, pp. 88-99, in Phage and the Origins of Molecular Biology, J. Cairns, G.S. Stent, and J.D. Watson eds., Cold Spring Harbor Laboratory Press, 1966.

(8) Wollman, Elie L, Bacterial Conjugation, pp. 216-225, in Phage and the Origins of Molecular Biology, J. Cairns, G.S. Stent, and J.D. Watson eds., Cold Spring Harbor Laboratory Press, 1966.

(9) “The Phage in the Letter,” Posted on the blog November 4, 2013.

(9) Francois Jacob, Nobel Lecture, December 11, 1965.

(11) Norkin, Leonard C., Virology: Molecular Biology and Pathogenesis, ASM Press, 2010.

Andre Lwoff

Louis Pasteur: One Step Away from Discovering Viruses

Louis Pasteur (1822-1895) is the subject of our first posting of the New Year. Pasteur was history’s greatest microbiologist and, perhaps, its most famous medical scientist. Pasteur was also an early figure in the history of virology for his 1885 discovery of a rabies vaccine; only the second antiviral vaccine and the first attenuated one (see Aside 1). However, the main point of this tale is that Pasteur let pass an especially propitious opportunity to discover that the rabies agent is one of a previously unrecognized class of microbes; a class that is fundamentally different from the already known bacteria. Its members are submicroscopic and grow only inside of a living cell. Pasteur was just one step away from discovering viruses.

Louis Pasteur
Louis Pasteur

[Aside 1: Attenuation is the conversion of a pathogenic microbe into something that is less able to cause disease, yet is still able to induce immunity. Edward Jenner’s 1798 smallpox vaccine, the world’s first vaccine, as well as the first antiviral vaccine, was not based on the principle of attenuation. Instead, it contained live, unmodified cowpox virus. Although hardly understood in Jenner’s day, his smallpox vaccine worked because cowpox, which is not virulent in humans, is immunologically cross-reactive with smallpox. Thus, the relatively benign cowpox virus induced immunity against the related, deadly smallpox virus (1).]

The distinctive nature of viruses would first begin to be revealed in 1887 by a scientist of much less renown than Pasteur; the Russian microbiologist Dmitry Ivanovsky. The virus concept would be further advanced in 1898 by the accomplished Dutch botanist Martinus Beijerinck (2). In any case, to better appreciate how anomalous it was that Pasteur did not discover viruses, we review the greatness of his earlier achievements. After that, we consider the opportune circumstance that he let go by.

Pasteur was a chemist by background. Thus, his first major scientific discovery, at 26 years of age, was as a chemist. It was his 1847 discover of molecular asymmetry; that certain organic molecules exist in two alternative molecular structures, each of which is the mirror image of the other. Additionally, pairs of these asymmetric molecules are chemically indistinguishable from each other, and balanced mixtures of them rotate the plane of polarized light.

Pasteur’s discovery of molecular asymmetry was one of the great discoveries in chemistry. Yet his research would take on a momentous new focus when he began to investigate the chemistry of fermentations. This new course was inspired by the fact that while asymmetric molecules are not generated in the laboratory, they are found in the living world. And, since asymmetric molecules are found among fermentation products, Pasteur hypothesized that fermentation is a biological process, which he proceeded to demonstrate in 1857, basically by showing that fermentation products did not arise in nutrient broth if any microbes that might have been present were either killed by heating or removed by filtration. What’s more, he showed that specific fermentations are caused by specific microorganisms. Additionally, he discovered that fermentation is usually an anaerobic process that actually is impaired by oxygen; a phenomenon known as the “Pasteur effect.” And, he put forward the notion of aerobic versus anaerobic microbes.

Pasteur put his experience studying fermentations to practical use when he came to the rescue of the French wine industry, which was on the verge of collapse because of the wine becoming putrefied. Pasteur showed that the problem was due to bacterial contamination, and then showed that the putrefaction could be prevented by heating the wine to 50 to 60 °C for several minutes; a procedure we now refer to as pasteurization. Wines are seldom pasteurized today because it would kill the organisms responsible for the wines maturing. But, as we know, pasteurization is applied to many contemporary food products, especially milk. Pasteur also aided the beer industry by developing methods for the control of beer fermentation.

Pasteur’s study of fermentations led to an experiment of historic significance for biology in general. In the 1860s, the ancient notion that life can arise spontaneously from nonliving materials, such as mud or water, was still widely believed. The emerging awareness of microbes in the 1860s did not change this belief. Instead, it led to the idea that fermentations and putrefactions result from the spontaneous generation of microbes. In 1862, Pasteur unequivocally dispelled this belief by a simple yet elegant experiment in which he made use of a flask that had a long bending neck that prevented contaminants from reaching the body of the flask. If the broth in the flask was sterilized by boiling, and if the neck remained intact, then the broth remained sterile. But, if the neck of the flask was broken off after the boiling, then the broth became opaque from bacterial contamination.

Taken alone, Pasteur’s achievements that are enumerated above would have been sufficient to have ensured his lasting fame. Nevertheless, Pasteur’s greatest successes were yet to come. In 1867 he put forward the “germ theory of disease.” By this time, the existence of a variety of microorganisms, including bacteria, fungi, and protozoa, was already well established. Pasteur’s new proposal, that microorganisms might produce different kinds of diseases, was inspired by his earlier experimental findings that different microorganisms are associated with different kinds of fermentations, and by his 1865 finding that a microorganism was responsible for a disease in silkworms that was devastating the French silk industry.

After Pasteur proposed his germ theory of disease, Robert Koch (another giant in the history of medical microbiology) established that anthrax in cattle is caused by a specific bacterium, Bacillus anthracis. Koch had taken a sample from diseased cattle and then used his new method for isolating pure bacterial colonies on solid culture media to generate a pure culture of B. anthracis. Next, he inoculated healthy animals with a portion of the pure culture. The healthy animals then developed anthrax. Finally, he re-isolated B. anthracis from the inoculated animals. This sequence of isolation, infection, and re-isolation constitutes Koch’s famous postulates, which provide the experimental basis for establishing that a specific microorganism is responsible for a specific disease.

Even after Pasteur confirmed Koch’s anthrax findings in 1877, some members of the medical establishment still rejected the germ theory of disease, mainly because Pasteur was a chemist by background, rather than a physician. Nevertheless, Joseph Lister, an English surgeon, admired Pasteur’s work on fermentation and was impressed by Pasteur’s disproving of spontaneous generation. Based on Pasteur’s demonstration of the ubiquity of airborne microorganisms (another of his noteworthy achievements), Lister reasoned that infections of open wounds are due to microorganisms in the environment. The aseptic techniques that Lister then introduced were responsible for dramatically reducing infections during surgery.

The following is one of my favorite parts of this story. In 1879, Pasteur made his first important contribution to vaccinology, when he discovered, by accident, that he could attenuate the bacterium responsible for chicken cholera (now known to be a member of genus Pasteurella), and then use the attenuated microbe as a vaccine. It happened as follows. Pasteur instructed his assistant, Charles Chamberland, to experimentally inject chickens with the cholera bacterium so that he, Pasteur, might observe the course of the disease. Then, just before a summer holiday break, Pasteur directed Chamberland to inject the chickens with a fresh culture of the bacteria. Chamberland may have been preoccupied with thoughts of the upcoming holiday, because he forgot to inject the chickens before leaving. When he returned a month later, he carried out Pasteur’s instructions, except that he injected the chickens with the now aged bacteria. What happened next was most important. The chickens that were inoculated with the aged culture developed only a very mild form of the disease. After that, Pasteur had Chamberland inject those same chickens with freshly grown, presumably virulent bacteria. The chickens still did not develop disease.

It is not clear why Pasteur instructed Chamberland to inoculate the freshly grown culture into the chickens that earlier had received the aged culture. Perhaps it was an accident, or perhaps Pasteur saw an opportunity to carry out a possibly interesting experiment. (The chickens had survived a mild infection by the aged culture. Might they now be resistant to freshly grown virulent bacteria?) In any case, Pasteur repeated the entire sequence of inoculating the chickens with an aged culture and then challenging them with a fresh culture. The outcome was the same as before.

Pasteur correctly surmised that the aging process (actually, oxidation by exposure to air) had attenuated the bacteria. And, he learned by experimentation that the virulence of the cholera microbe could be reduced to any desired extent by controlling its exposure to air. Most importantly perhaps, he discovered that the attenuated bacteria could induce resistance to the virulent bacteria and, consequently, could be used as a vaccine. Pasteur’s chicken cholera vaccine was the first vaccine deliberately created in a laboratory. What’s more, it was the first attenuated vaccine. See Aside 2.

[Aside 2: During the years that Pasteur was carrying out his vaccine studies, nothing was known regarding the physiological basis of immunity, or the determinants of virulence, or of mutations, or the underlying mechanism of attenuation that changed a deadly microbe into a harmless one that still could induce immunity. Considering the intellectual milieu in which Pasteur carried out his investigations, it is all the more remarkable that he achieved so much. And while Pasteur’s interpretations for how his attenuated vaccines worked were far from accurate, they are still impressive for their plausibility. Initially, he thought that the attenuated organisms might simply compete with the virulent organisms for a limited availability of nutrients in the host. Later, he thought that the attenuated organisms might release a toxin that blocked growth of the virulent organisms. The notion, that the host might actually initiate its own defense, began to emerge in 1890 when Emil von Behring and Shibasaburo Kitasato discovered that a host factor neutralized the diphtheria toxin. Kitasato then put forward the theory of humoral immunity, proposing that a host serum factor could neutralize a foreign antigen. In 1891 Paul Ehrlich used the term “antibody” for the first time, in reference to those serum factors.]

This account of the cholera vaccine brings to mind Pasteur’s famous remark, “Chance only favors the prepared mind.” Yet in the context of our larger story, it is an ironic statement, considering that Pasteur later missed an auspicious opportunity to discover viruses. But, before getting to that, we briefly note Pasteur’s work on his anthrax vaccine.

In 1879 Pasteur began to develop an anthrax vaccine, which, like the cholera vaccine, would be based on his principle of attenuation. And, as in the case of the cholera vaccine, Pasteur attenuated the anthrax bacillus by exposing it to oxygen. [History records that Pasteur and his assistants developed a second approach to attenuate the anthrax bacillus, based on their discovery that when the bacilli are cultivated at 42 or 43 degrees centigrade, they do not develop the endospores that are necessary to cause a virulent infection.] In 1881 Pasteur carried out a dramatic public demonstration of the effectiveness of his air-oxidized anthrax vaccine in livestock, causing many doubters to accept the validity of his work. See Aside 3 and the end note.

[Aside 3: Currently, the only FDA-licensed anthrax vaccine for use in humans is BioThrax, produced by Emergent BioDefense Operations Lansing Inc. BioThrax is generated from an avirulent, nonencapsulated mutant of B. anthracis. It does not contain any living organisms. As suggested by the name of the manufacturer, BioThrax was produced mainly for the U.S. Department of Defense, for use in case B. Anthracis might be used as a biological weapon. Thus, BioThrax is not available to the public. People who are exposed to B. anthracis are now treated with antibiotics (e.g., ciprofloxacin and doxycycline).]

Pasteur turned his attention to rabies in1880, when the problem of rabid dogs in Paris was getting out of hand. Once again Pasteur sought to develop a vaccine, and once again he wanted to apply the principle of attenuation. But, early on, he found that he could not grow the rabies agent in pure culture. Thus, he was not able to isolate the rabies agent. Moreover, he would need to devise new procedures if he was to grow and attenuate it. His solution was to develop methods for cultivating the rabies agent in the spinal cords of live rabbits. His method for attenuation was then suggested by his assistant, Emile Roux, who had been studying survival of the rabies agent in pieces of rabbit spinal cord that he suspended inside a flask. Following Roux’s example, Pasteur attenuated the rabies agent by air-desiccating spinal cords taken from experimentally infected rabbits that earlier had died of rabies. Each successive day of desiccation resulted in greater attenuation of virulence, such that an extract from a spinal cord aged for 14 days could no longer transmit the disease. What’s more, those extracts could be used as inoculums that prevented rabies in dogs that later were challenged with the virulent microbe.

Pasteur, himself, took saliva samples from rabid dogs. In one such incident, he used a glass tube to suck up a few drops of deadly saliva from the mouth of a mad, squirming bulldog that was held down on a table by two assistants. The assistants wore heavy leather gloves.

Here is another of my favorite parts of this story. In 1885, nine-year-old Joseph Meister was bitten repeatedly by a rabid dog. Young Joseph’s desperate mother then brought her son to Pasteur, hoping that he might help Joseph. But, any attempt by Pasteur to treat the boy was sure to provoke controversy. Pasteur was not a medical doctor. Moreover, his rabies vaccine had never been successfully used in humans. Furthermore, attenuation and vaccination were still new and contentious concepts. For these reasons, Pasteur rejected many earlier requests for help from people in France, and from abroad as well. But, in Joseph’s case, Pasteur relented, convinced that the boy would die if he did not intercede.

Pasteur gave young Joseph a series of 13 injections, one each day, in which each successive injection contained a less-attenuated (stronger) virus. Pasteur dreaded inoculating Joseph with the last shot in the series; a one-day-old vaccine that was strong enough to kill a rabbit. Emile Roux wanted no part in this episode and, in fact, withdrew from the rabies study because of it. But, Joseph never developed rabies, and millions of people subsequently received Pasteur’s anti-rabies treatments. [Pasteur’s attenuated rabies vaccine may not have been entirely safe for humans. Modern rabies vaccines are generally killed virus vaccines, prepared by chemically inactivating tissue culture lysates.] See Asides 4 and 5.

[Aside 4: Post-infection rabies vaccination works and, indeed, is necessary because (for reasons that are still not entirely clear) the human immune response against a natural rabies infection is not able to prevent the virus from reaching the central nervous system, at which point the infection is invariably fatal. Importantly, the incubation period between the time of the bite and the appearance of disease can be more than several months, and is never less than two weeks. Consequently, there is a substantial window of opportunity for the vaccine to cause the virus to be inactivated at the site of the bite.]

[Aside 5: In 1888, Emile Roux, working at the Pasteur Institute (see below), would confirm the existence of the diphtheria toxin by showing that injecting animals with sterile filtrates of liquid cultures of Corynebacterium diphtheriae caused death with a pathology characteristic of actual diphtheria.]

Pasteur worked hard to isolate the rabies agent, but he wrongly presumed that he should be able to grow it in pure culture. Finally, in 1884, he conceded that he had not been able to isolate and cultivate the rabies agent in a laboratory media. So, might that failure alone have been sufficient to cause Pasteur to think of the rabies agent in new terms? Perhaps not, since, at the time, the inability to cultivate a microbial pathogen was assumed to be a laboratory failure, rather than a reason to hypothesize that that the agent was something other than a bacterium. [Even with the eventual awareness of the uniqueness of viruses, the inability of virologists to cultivate viruses outside of an animal would remain a mystery, as well as an obstacle, well into the early 1930s (3).]

Pasteur also got sidetracked while trying to isolate the rabies agent. In 1880 he injected a rabbit with the saliva of a child who died of rabies. He then examined the blood of the rabbit after it too succumbed to rabies. Using his microscope, Pasteur in fact saw a microbe in the rabbit’s blood, which he thought might be the rabies agent. However, he later found the same microbe in the saliva of normal children. Ironically, this microbe, which Pasteur at first thought might be the rabies agent, was actually Pneumococcus pneumoniae, a major bacterial pathogen that was correctly identified several years later by Albert Frankel. Thus, Pasteur missed the opportunity to identify a bacterial pathogen that is much more important in humans than rabies virus. Moreover, and importantly, Pasteur never did see the actual rabies agent under his microscope. Thus, he was aware that the rabies agent might be unusually small in comparison to the usual bacteria.

Here is another bit of irony. The item (apparatus?) that initially played the key role in distinguishing viruses from bacteria was invented in Pasteur’s laboratory. It was the unglazed terra cotta filter, conceived by Charles Chamberland, which he used to provide a good supply of sterile water for Pasteur’s lab. Chamberland allegedly developed these bacterium-proof filters while experimenting with a broken clay pipe that he bought from his tobacconist.

Bearing in mind that Pasteur was never able to grow the rabies agent in pure culture, and that he never saw the rabies agent under his microscope, might he have thought that it might be a submicroscopic infectious agent that is different from bacteria in some fundamental way? I have not come across any definitive answer to that question. But, I feel safe to say that it is unlikely that anyone other than Pasteur might have seriously considered that possibility. Regardless, Pasteur did not take the next logical step, which would have been to see if the rabies agent might pass through Chamberland’s filters. Had he done so, he could have isolated the rabies agent from the rabbit spinal cords, and he would have discovered “filterable viruses” (see below).

That crucial step was taken for the first time in 1887 by the Russian bacteriologist, Dmitry Ivanovsky, who used Chamberland filters in his investigations into the cause of tobacco mosaic disease. Ivanovsky could not propagate the tobacco mosaic agent (later known as the tobacco mosaic virus) in pure culture. However, because of his finding that the agent could actually pass through Chamberland’s filters, Ivanovsky is sometimes credited for discovering viruses. Yet Ivanovsky did not accept his own results. He still presumed that the disease was caused a bacterium, and he thought that the filters were defective or, instead, that the disease was due to a toxin produced by the bacterium.

In 1898, Martinus Beijerinck, unaware of Ivanovsky’s earlier work, also could not see or cultivate the tobacco mosaic agent. In addition, he too found that the agent passed through Chamberland filters. Beijerink expected, and perhaps even hoped that the filters would remove the agent from diseased plant extracts, so that he might prove it to be a bacterium. But despite his possible disappointment, Beijerinck went one major step further. He demonstrated that the filtered sap from a diseased plant did not lose its ability to cause disease after being diluted by repeated passage through new healthy plants. Consequently, the filterable agent was replicating in the plant tissue and, thus, could not be a toxin.

Little is recorded about Ivanovsky, aside from his four-page report on the tobacco mosaic disease (see Aside 6). In contrast, Beijerinck was a major scientist, who made numerous important contributions, including the discovery of nitrogen-fixing bacteria and bacterial sulfate reduction (4). Yet even Beijerinck found it difficult to conceive that the filterable, incredibly small, submicroscopic tobacco mosaic agent might be particulate in nature. Instead, he famously described it as a “contagious living fluid.” Nonetheless, Beijerinck, a botanist by background, is often considered to be the first virologist.

[Aside 6: Ivanovsky’s four-page paper would be unremarkable if it were not for the single sentence, “Yet I have found that the sap of leaves attacked by the mosaic disease retains its infectious qualities even after filtration through Chamberland filters.”]

Pasteur was probably unaware of Ivanovsky’s findings, and he did not live long enough to know of Beijerinck’s. So, we do not know what he might have made of their results. Regardless, Pasteur remained one step away from making these discoveries himself.

In 1898, after the announcement of Beijerinck’s findings, Friederich Loeffler and Paul Frosch isolated the foot and mouth disease virus; the first virus isolated from animals. Next, in 1901, in Cuba, U.S. Army doctor Walter Reed isolated yellow fever virus (5); the first pathogenic virus of humans to be isolated. In 1903, Paul Remlinger, working at the Constantinople Imperial Bacteriology Institute, filtered and then isolated rabies virus. Despite these early achievements, it was not until 1938 that the development of the electron microscope made it possible to resolve that viruses are indeed particulate, rather than liquid in nature. See Aside 7.

[Aside 7: The term “virus” indeed appears in the scientific literature of Pasteur’s day. However, at that time “virus” referred to any microbe that might cause disease when inoculated into a susceptible human or animal. By the 1890s, the term “filterable virus” came into use, meaning an infectious agent which, like the tobacco mosaic virus, passed through filters that retained bacteria. But, bearing in mind that there was not even a consensus regarding the identity of the genetic material until the early 1950s, there would be no clear understanding of viruses until then. In fact, the classic, early 1950s blender experiment of Alfred Hershey and Martha Chase, which featured bacteriophage T4, played a key role in establishing DNA as the genetic material, while also elucidating the essentials of virus replication (2).]

In 1887 Louis Pasteur founded the Institute in Paris that bears his name. A minor irony is that the Pasteur Institute was founded as a rabies vaccine center. The Institute has since been the site of numerous major discoveries in infectious diseases. But we underscore here that it was the site where, in 1910, Constantin Levaditi and Karl Landsteiner demonstrated that poliomyelitis is caused by a filterable virus, and where Félix d’Herelle in 1917 discovered bacteriophages. And it was also the site where, in 1983, Luc Montagnier and Françoise Barré-Sinoussi were the first to isolate HIV (6).

In a fitting end to our story, when Joseph Meister grew up, he became the gatekeeper of the Pasteur Institute. Meister was still minding the gate at age sixty four when, in 1940, the Nazis invaded Paris. Legend has it that when Nazi soldiers arrived at the Institute and ordered Meister to open Pasteur’s crypt, rather than surrendering Pasteur’s resting place to the Nazis, Meister shot himself (7).

Pasteur Institute: Museum and Crypt
Pasteur Institute: Museum and Crypt

End note:

Science historian, Gerald L. Geison, wrote a controversial revisionist account of Pasteur’s achievements, that was based on Geison’s reading of Pasteur’s laboratory notes (8). Geison undermines Pasteur’s integrity and discredits some of his major accomplishments. For example, Geison asserts that Pasteur surreptitiously used the oxidation procedure of French veterinary surgeon, Henry Toussaint, when preparing his own widely acclaimed anthrax vaccine for its public demonstration.

Max Perutz, who shared the 1962 Nobel Prize for Chemistry with John Kendrew for their studies of the structures of hemoglobin and myoglobin, reviewed Geison’s book for The New York Review of Books (December 21, 1995). Perutz’s review, entitled The Pioneer Defended, contains a vigorous rebuttal of Geison’s claims. Geison responded to Perutz’s review in the April 4, 1996 issue of The New York Review of Books. Perutz’s counter-response immediately follows.

I make note of all this because Geison’s uncertain assertions are reported as unqualified fact in some accounts of Pasteur’s work. And, while Perutz’s representations are not entirely accurate, the review, the response, and the counter-response make a very interesting read.

References:

(1) Edward Jenner and the Smallpox Vaccine, Posted on the blog September 16, 2014.

(2) Norkin, L. C. Virology: Molecular Biology and Pathognesis, ASM Press, 2010. Chapters 1 and 2 review key developments towards the understanding of viruses.

(3) Ernest Goodpasture and the Egg in the Flu Vaccine, Posted on the blog November 26, 2014.

(4) Chun, K.-T., and D. H. Ferris,  Martinus Willem Beijerinck (1851-1931) Pioneer of general microbiology, ASM News 62, 539-543, 1996.

(5) The Struggle against Yellow Fever: Featuring Walter Reed and Max Theiler, Posted on the blog May 13, 2014.

(6) Who Discovered HIV?, Posted on the blog January 23, 2014.

(7) Dufour, H. D., and S. B. Carroll, (2013), History: Great myths die hard, Nature 502, 32–33. This note contains an update on the myth.

(8) Geisen, G. L., The Private Science of Louis Pasteur, Princeton University Press, 1996.

Ernest Goodpasture and the Egg in the Flu Vaccine

There is a cautionary note on the info sheet accompanying the influenza vaccine, which advises individuals who are allergic to eggs to speak with their doctors before receiving the vaccine. As most readers know, the reason for the warning is that the usual flu vaccine is grown in embryonated chicken eggs.

[Aside 1: The current trivalent influenza vaccine is prepared by inoculating separate batches of fertile chicken eggs; each with one of the three influenza strains (representing an H1N1, an H3N2, and a B strain) recommended by the WHO for the upcoming winter flu season. The monovalent viral yields are then combined to make the trivalent vaccine.]

But, why chicken eggs, and how did this state of affairs come to be? The backdrop to this tale is that until the third decade of the twentieth century, virologists were still searching for fruitful means to cultivate viruses outside of a live laboratory animal. This was so despite the fact that, as early as 1907, researchers had been developing procedures for maintaining viable tissues in culture. And, soon afterwards, virologists began to adapt tissue cultures as substrates for propagating viruses.

Yet as late as 1930, there were still only two antiviral vaccines—the smallpox vaccine developed by Edward Jenner in 1798 (1) and the rabies vaccine developed by Louis Pasteur in 1885. Bearing in mind that Jenner’s vaccine preceded the germ-theory of disease by a half century, and that Pasteur’s vaccine came 15 years before the actual discovery of viruses (as microbial agents that are distinct from bacteria), the development of these first two viral vaccines was fortunate indeed (2).

The principal factor holding up the development of new viral vaccines was that viruses, unlike bacteria, could not be propagated in pure culture. Instead, for reasons not yet understood, viruses could replicate only within a suitable host. And, notwithstanding early attempts to propagate viruses in tissue culture (reviewed below), developments had not yet reached a stage where that approach was fruitful enough to generate a vaccine. How then were Jenner and Pasteur able to produce their vaccines? See Aside 2 for the answers.

[Aside 2: Jenner, without any awareness of the existence of infectious microbes, obtained his initial inoculate by using a lance to pierce a cowpox postule on the wrist of a young milkmaid, Sarah Nelmes. Jenner then propagated the vaccine, while also transmitting immunity, by direct person-to-person transfer. (The rationale underlying Jenner’s vaccine, and his story, is told in detail in reference 1.)

Jenner’s live cowpox vaccine protected against smallpox because cowpox, which produces a relatively benign infection in humans, is immunologically cross-reactive with smallpox. Thus, inoculating humans with cowpox induces immunity that is active against cowpox and against smallpox as well. Jenner’s discovery of the smallpox vaccine, while not entirely fortuitous, was still providential, since immunity per se, as well as microbes, were unknown in Jenner’s day.

Following a successful worldwide vaccination program, smallpox was officially declared to be eradicated in 1977. The smallpox vaccine currently stockpiled in the United States contains live vaccinia; a virus that is immunologically related to cowpox and smallpox. Like cowpox, vaccinia causes a mild infection in humans.

The existing smallpox vaccine was grown in the skin of calves. It is now more than 40 years old and has not been used for years, but it is still believed to be effective.

Pasteur (probably the greatest and most famous microbiologist) was a pioneer of the germ theory of disease. Yet he developed his rabies vaccine more than a decade before the discovery of viruses. He did so by applying the same principle that he used earlier to produce a vaccine against cholera. That is, he “attenuated” the rabies agent. He began with virus that was contained in an extract from a rabid dog. Pasteur attenuated the virus for humans by successively passing extracts in the spinal cords of live rabbits, and then aging the last extracts in the series. Modern rabies vaccines are generally killed virus vaccines, prepared by chemically inactivating tissue culture lysates.]

In the years following the pioneering 19th century contributions of Pasteur, Koch, and Lister, and with the widespread acceptance of the germ theory of disease, microbiologists (that is, bacteriologists) appreciated the importance of working with “pure cultures” that could be grown in a sterilized medium. Yet this was proving to be impossible in the case of viruses. Moreover, as late as the 1930s, it was not understood why that should be so

At the very least, virologists would have liked to be able to cultivate viruses outside of a living animal host. The possibility of achieving that goal began to emerge when Ross G. Harrison, working at Johns Hopkins in 1907, became the first researcher to maintain bits of viable tissue outside of an animal. Harrison maintained frog neuroblasts in hanging drops of lymph medium. What’s more, under those conditions, the neuroblasts gave rise to outgrowths of nerve fibers.

In 1913, Edna Steinhardt became the first researcher to cultivate (or at least maintain) a virus (cowpox) in a tissue culture. Steinhardt did this by infecting hanging-drop cultures with corneal extracts from the eyes of cowpox-infected rabbits and guinea pigs. However, there was no methodology at the time for Steinhardt to determine whether the virus might have replicated in her tissue cultures.

In 1912, Alexis Carrel, working at the Rockefeller Institute, began a two-decade-long experiment that significantly increased interest in tissue culture. Carrel maintained tissue fragments from an embryonic chicken heart in a closed flask, which he regularly supplied with fresh nutrients. Later, he claimed that he maintained the viability of the culture for more than 20 years; well beyond the normal lifespan of a chicken. See Aside 3.

[Aside 3: Carrel’s experimental results could never be reproduced. In fact, in the 1960s, Leonard Hayflick and Paul Moorhead made the important discovery that differentiated cells can undergo only a limited number of divisions in culture before undergoing senescence and dying. It is not known how Carrel obtained his anomalous results. But, Carrel was an honored, if controversial scientist, having been awarded the 1912 Nobel Prize in Physiology or Medicine for pioneering vascular suturing techniques. In the 1930s Carrel developed an intriguing and close friendship with Charles Lindbergh, which began when Lindbergh sought out Carrel to see if Carrel might help Lindbergh’s sister, whose heart was damaged by rheumatic fever. Carrel could not help Lindbergh’s sister, but Lindbergh helped Carrel build the first perfusion pump, which laid the groundwork for open heart surgery and organ transplants. Carrel and Lindbergh also co-authored a book, The Culture of Organs. In the 1930s, Carrel, promoted enforced eugenics. During the Second World War, Carrel, who was French by birth, helped the Vichy French government put eugenics policies into practice. Moreover, he praised the eugenics policies of the Third Reich, leading to inconclusive investigations into whether he collaborated with the Nazis. Carrel died in November, 1944.]

In 1925 Frederic Parker and Robert Nye, at the Boston City Hospital, provided the first conclusive evidence for viral growth in a tissue culture. The virus was a strain of herpes simplex, which Parker and Nye received in the form of an extract from Ernest Goodpasture; soon to be the major character in our story. Parker and Nye established their first culture from the brain of a rabbit that was inoculated intracerebrally with an extract from an infected rabbit brain. The animal was sacrificed when in a convulsive state, and its brain was then removed aseptically. Small pieces of normal rabbit testes were added to pieces of brain in the cultures, to provide another potential host cell for the virus. Virus multiplication was demonstrated by inoculating diluents of subculture extracts into laboratory animals. A 1:50,000 diluent was able to transmit the infection.

At this point in our chronology, the pathologist Ernest Goodpasture, and the husband-wife team of Alice and Eugene Woodruff, enters our story. Goodpasture’s principal interest was then, as always, in pathology. He became interested in viruses while he was serving as a Navy doctor during World War I. But his focus was on the pathology of the 1918 influenza pandemic, which he studied in the first sailors stricken by the infection (3). He was later interested in herpetic encephalitis, and in how rabies virus made its way to the central nervous system, but always from the perspective of a pathologist.

Ernest Goodpasture. (I was unable to find a picture of Alice Woodruff.)
Ernest Goodpasture. (I was unable to find a picture of Alice Woodruff.)

In 1927, Eugene Woodruff was a newly graduated physician who joined Goodpasture in the Pathology Department at Vanderbilt University for training as a pathologist. Eugene’s wife, Alice, a Ph.D., came to the Vanderbilt Pathology Department a year later, as a research fellow in Goodpasture’s laboratory.

Goodpasture set Eugene Woodruff to work on fowlpox; a relative of smallpox, which, unlike cowpox, can not infect humans. Goodpasture was interested in the cellular pathology of fowlpox infection; specifically, in the nature of the inclusion bodies seen in fowlpox-infected cells. Using a micropipette, Woodruff was able to pick single inclusion bodies from infected chicken cells, and to then determine that inclusion bodies are intracellular crystalline arrays of the virus.

More apropos to our story, in the late 1920s, virologists still could not generate large amounts of virus that were free of bacteria and contaminating tissue elements. For that reason, Goodpasture believed that future important advancements in virology would require the development of methods to grow large amounts of virus in pure culture; an impossible goal. In any case, Goodpasture delegated Alice Woodruff to develop a method for growing fowlpox outside of a live chicken.

Goodpasture had already adapted Carrel’s tissue culture methods, which he used to maintain chick kidney tissue in culture. So, Alice’s first experiments were attempts to get fowlpox to propagate in cultures of chick kidney tissue. However, the virus stubbornly declined to grow in the tissue cultures. Goodpasture then suggested to Alice that she try to grow the virus in embryonated chicken eggs. But why did Goodpasture make that suggestion?

The answer isn’t clear. But, back in 1910, Peyton Rous and colleague James Murphy, at the Rockefeller Institute, fruitfully made use of fertile chick eggs to cultivate a virus, as described in Aside 4. However, Rous’ accomplishments, which eventually would be recognized as huge, were largely ignored for the next 50 or so years. (The reasons are discussed in reference 4.) Goodpasture may well have been unaware of Rous’ earlier work when he suggested to Alice that she try to cultivate fowlpox in chicken eggs. If so, then his suggestion to Alice may have been an original idea on his part, perhaps inspired by his thinking of the chick embryo as a sterile substrate that is enclosed in a naturally sterile container. On the other hand, he and Alice did note the earlier work of Rous and Murphy in the 1931 report of their own work. (In that paper, they state: “The production of experimental infection in the chorio-allantoic membrane has, however, been done only in the one instance where Rous and Murphy grew the virus of the Rous sarcoma.”). In any case, the chick embryo method for growing viruses had lain dormant for twenty years.

[Aside 4: Rous and Murphy cut a small window into the shells of six-to-sixteen-day-old embryonated chicken eggs, and then placed a bit of a filtered, cell-free extract from a chicken sarcoma into each. By one week’s time there was a tumor mass growing in each of the inoculated embryos. These studies led to Rous’ 1911 report of a filterable, infectious agent, eventually named the Rous sarcoma virus, which causes sarcomas in chickens. The Rous sarcoma virus was the first virus known to cause solid tumors and, moreover, it was the prototype of a virus family that eventually would be known as the retroviruses (4).]

Alice Woodruff’s procedure for infecting the chicken eggs began with her making a small window in the egg shell, at the site of the air sac. (An egg cup served as the operating table, and the window was cut with a dentist’s drill.) She then inoculated the viral extract into the outermost layer of the chorio-allantoic membrane, which encloses the embryo and provides an air channel into its body. Alice then closed the window with a piece of glass, held in place with Vaseline.

Alice tried to maintain sterility at all stages of her procedure. Yet despite the elegance of her techniques, she had nothing to show for these efforts except dead embryos that were overgrown with mold or bacteria. She then turned to her husband, Eugene, who was working in a separate laboratory, down the hall from her lab.

Alice and Eugene, working together, developed procedures to sterilely remove fowlpox lesions from the heads of chicks. In brief, the chick heads were shaved and then bathed in alcohol. Then, the lesions were excised with sterile instruments. Next, the excised lesions were tested for bacterial or fungal contamination by incubating fragments in nutrient broth. If a lesion was sterile by that test, it was deemed fit to be inoculated into the eggs.

Eugene further contributed to the effort by applying a technique that he developed earlier; picking out individual inclusion bodies from fowlpox-infected cells. When he discovered that the inclusion bodies could be disrupted into individual virus particles by incubating them in trypsin, he was able to provide Alice with virtually pure virus that she could inoculate the eggs with.

As Greer Williams relates in Virus Hunters (5): “Then, one morning when she peeked into the window of an egg that had been incubating for about a week after she had infected it with the virus, she saw something different. This chick embryo was still alive…She removed the embryo from the shell and examined it. It had a swollen claw. ‘Could this be due to fowlpox infection?’…She went to Goodpasture and put the same question to him…”

In Alice’s own words, “I can’t forget the thrill of that moment when Dr. Goodpasture came into my lab, and we stood by the hood where the incubator was installed and I showed him this swollen claw from the inoculated embryo (5).”

The swollen claw indeed resulted from the fowlpox infection. This was shown by the fact that when bits of the swollen tissue were transferred to other embryos, they in turn induced more swollen tissue. Moreover, these swollen tissues contained fowlpox inclusion bodies. Additionally, when transferred to adult chickens, those bits of swollen tissue produced typical fowlpox lesions.

During the next year, Goodpasture, Alice Woodruff, and Gerritt Budding (a lab assistant, who dropped out of medical school to participate in the chick embryo work) reported that cowpox and herpes simplex viruses could also be grown in the embryonated chicken eggs.

Later studies by Goodpasture and Buddingh showed that each embryonated chicken egg could produce enough vaccinia to produce more than 1,000 doses of smallpox vaccine. They also showed, in a case-study involving 1,074 individuals, that the chick-grown smallpox vaccine works as well in humans as the vaccine produced by inoculating the skin of calves. Regardless, the chick vaccine never caught on to replace the long-established, but cruder calf-grown vaccine (see Aside 2).

Goodpasture placed Alice’s name ahead of his own on their report describing the propagation of fowlpox in chicken eggs. Alice says that Goodpasture was “over-generous” in that regard. Howevever, much of the day-to-day lab work resulted from her initiatives. Eugene’s name also came before Goodpasture’s on the report describing the inclusion body study.

Shortly after completing these studies, Alice left research to raise a family. Eugene’s name also disappeared from the virus literature. But in his case that was because his interests turned to tuberculosis.

In 1932, soon after the above breakthroughs in Godpasture’s laboratory,  Max Theiler and Eugen Haagen developed their yellow fever vaccine (6), which initially was generated in embryo tissue from mice and chickens. But, starting in 1937, production of the yellow fever vaccine was switched to the embryonated egg method, in part, to “cure” the live yellow fever vaccine of its neurotropic tendencies.

Recall our introductory comments regarding the warning that individuals allergic to eggs should get medical advice before receiving the standard flu vaccine. In 1941, Thomas Francis, at the University of Michigan, used embryonated chicken eggs to produce the first influenza vaccine (see Asides 5 and 6). Remarkably, even today, in the era of recombinant DNA and proteomics, this seemingly quaint procedure is still the preferred means for producing the standard trivalent flu vaccine (see Aside 1).

[Aside 5: Thomas Francis produced his 1941influenza vaccine in response to urging by U.S. Armed Forces Epidemiological Board. With the Second World War underway in Europe and Asia, and with the 1918 influenza pandemic in mind, there was fear that if an influenza epidemic were to emerge during the upcoming winter, it might impede the military training that might be necessary. An epidemic did not materialize that winter, but the vaccine was ready, and we were at war.]

[Aside 6: Thomas Francis was one of the great pioneers of medical virology. The same year that he developed his flu vaccine, Jonas Salk (recently graduated from NYU medical school) came to his laboratory for postgraduate studies. Francis taught Salk his methodology for vaccine development, which ultimately enabled Salk to develop his polio vaccine (7).]

Next, Hillary Koprowski developed a safer, less painful and more effective rabies vaccine that is grown in duck eggs, and that is still widely used. Why duck eggs? The reason is that duck eggs require four weeks to hatch, instead of the three weeks required by chicken eggs. So, duck eggs give the slow-growing rabies virus more time to replicate.

By any measure, the procedures for growing viruses in embryonated chicken eggs, developed by Ernest Goodpasture and Alice Woodruff, were a major step forward in vaccine development. Sir Macfarlane Burnet (a Nobel laureate for his work on immunological tolerance) commented 25 years later, “Nearly all the later practical advances in the control of viral diseases of man and animals sprang from this single discovery.”

Addendum 1: Several major advances in cell and tissue culture (the other means for growing viruses outside of an animal) happened after Woodruff and Goopasture reported the development of their embryonated egg method in 1931. For the sake of completeness, several of these are noted.

In 1933, George Gey, at Johns Hopkins, developed the roller tube technique, in which the tissue is placed in a bottle that is laid on its side and continuously rotated around its cylindrical axis. In that way, the media continually circulates around the tissue. Compared to the older process of growing tissues in suspension, the roller culture method allowed the prolonged maintenance of the tissues in an active state and, consequently, the growth of large amounts of virus. The roller tube technique also works very well for cell cultures that attach to the sides of the bottle. [Incidentally, Gey is probably best known for having established the HeLa line of human carcinoma cells from cancer patient, Henrietta Lacks. HeLa cells comprise the first known human immortal cell line and they have served as one of the most important tools for medical research. (See The Immortal Life of Henrietta Lacks, by Rebecca Skloot, 2010.)]

In 1948, John Enders, and colleagues Thomas Weller and Frederick Robbins, used Gey’s methods, to demonstrate for the first time that poliovirus could be grown in non-nervous tissue. This was significant because the potential hazard of injecting humans with nervous tissue was holding up the development of a polio vaccine.

Next, Renato Dulbecco and Marguerite Vogt, working at Caltech, developed procedures to grow large amounts poliovirus in cell culture, adding to the feasibility of an eventual polio vaccine (8). Additionally, Dulbecco and Vogt developed a plaque assay procedure to measure the titer of animal viruses grown in cell culture (7).

Addendum 2: The following excerpt tells of the chance encounter that led Howard Temin to become a virologist (4). Temin was the Nobel laureate who first proposed the retroviral strategy of replication, and who co-discovered reverse transcriptase.

“Howard Temin began working on Rous sarcoma virus in the 1950s, while a graduate student in Renato Dulbecco’s laboratory at Caltech (see reference 7 for more on Dulbecco). However, he worked under the direct supervision of Harry Rubin, an early star in the field, who was, at the time, a postdoctoral fellow in the Dulbecco lab. Nothing was known as yet about the replication of the RNA tumor viruses, as the retroviruses were then known. Moreover, little more was known about the molecular basis of cancer in the 1950s than was known in 1911, when Rous first isolated his virus; a state of affairs that would be much alleviated by future studies of the oncogenic retroviruses.

Rubin was a veterinarian by training, perhaps accounting for his somewhat unique appreciation of an oncogenic virus of chickens, well after even Rous himself had lost interest. And, Rubin was responsible for introducing other young investigators to the RNA tumor virus field, both at Caltech and later at UC Berkely.

Rubin’s mentorship of Temin began somewhat fortuitously, as follows. When they first met, Temin was actually doing his graduate research in another laboratory at Caltech, looking into the embryology of the innkeeper worm, Urechis caupo. But he was also serving as a laboratory assistant in the Caltech general biology course. In that capacity, he was dispatched to Dulbecco’s laboratory to obtain some fertilized chicken eggs for use in the general biology lab. Harry Rubin supplied the chicken eggs. But the chance visit from Temin gave Rubin the opportunity to tell Temin about the chicken sarcoma viruses that were being studied in the Dulbecco laboratory.

Rubin had just recently found that he could induce the neoplastic transformation of a normal chicken cell with a single Rous sarcoma virus particle. He then demonstrated that the transformed cell produced hundreds more transformed daughter cells in a week’s time. During their chance conversation, Rubin suggested to Temin that he (Temin) might make use of that observation to develop a quantitative tissue culture assay for Rous sarcoma virus. Sufficiently intrigued by Rubin’s proposition, Temin switched from embryology to virology and proceeded to develop a focus-forming cell culture assay for Rous sarcoma virus; an assay analogous in principle to a plaque assay. But instead of forming plaques of dead cells, the non-cytocidal Rous sarcoma virus induces the growth of visible foci of morphologically transformed neoplastic cells.”

[Addendum 3: Today, viruses are usually cultivated in readily available continuous cell lines. That said, when I first entered the field in 1970, as a postdoctoral studying the murine polyomavirus, my first task of the week was to prepare the baby-mouse-kidney and mouse-embryo primary cell cultures, which at that time served as the cellular host for that virus. This rather unpleasant chore was a reason I eventually turned to SV40, since I could grow that virus in continuous lines of monkey kidney cells.

References:

1. Edward Jenner and the Smallpox Vaccine, posted on the blog September 16, 2014.

2. Leonard C. Norkin, Virology: Molecular Biology and Pathogenesis, ASM Press, 2010. Chapter 1 tells how viruses were discovered and how their distinctive nature was brought to light.

3. Opening Pandora’s Box: Resurrecting the 1918 Influenza Pandemic Virus and Transmissible H5N1 Bird Flu, posted on the blog April 15, 2014.

4. Howard Temin: “In from the Cold,” posted on the blog December 14, 2013.

5. Greer Williams, Virus Hunters, Alfred A. Knopf, 1960.

6. The Struggle Against Yellow Fever: Featuring Walter Reed and Max Theiler, posted on the blog May 12, 2014.

7. Renato Dulbecco and the Beginnings of Quantitative Animal Virology, posted on the blog December 3, 2013.

8. Jonas Salk and Albert Sabin: One of the Great Rivalries of Medical Science, posted on the blog March 27, 2014.

The Struggle Against Yellow Fever: Featuring Walter Reed and Max Theiler

The first part of this posting tells how a U.S. Army medical board, headed by Walter Reed, confirmed that the transmission of yellow fever requires a mosquito vector. The second part tells the story of the yellow fever vaccine developed by Max Theiler.

Bearing in mind the enormous benefit to mankind of the polio vaccines developed by Jonas Salk and Albert Sabin (1), and that Maurice Hilleman developed nearly 40 vaccines, including those for measles, mumps, and rubella (2), it would appear remarkable that Theiler was the only one of these four individuals to be recognized by the Nobel committee. In fact, Theiler’s 1951 Nobel award was the only one ever given for a vaccine! In any case, while Theiler’s vaccine was a major step forward in the fight against yellow fever, it came after a perhaps more dramatic episode in the struggle against that malady. But first, we begin with some background.

Yellow fever was another of mankind’s great scourges. Indeed, it was once the most feared infectious disease in the United States. And, while we might want to say that science has “conquered” yellow fever, that statement would not be entirely accurate. Unlike polio and measles, which have nearly been eradicated by the vaccines against them, that is not so for yellow fever. The reason is as follows. Humans are the only host for polio and measles viruses. Consequently, those viruses might be completely eradicated if a sufficient percentage of humans were to comply with vaccination regimens. In contrast, the yellow fever virus infects monkeys that range over thousands of square miles in Africa and the Amazon jungle. Thus, even with massive vaccination of humans, it would be impossible to eliminate the yellow fever virus from the world.

According to the World Health Organization’s estimates, there are still about 200,000 cases of yellow fever per year, resulting in about 30,000 deaths, about 90% of which occur in Africa. The yellow fever virus itself is the prototype virus of the flavivirus family of single-stranded RNA viruses, which also includes dengue hemorrhagic fever virus, Japanese encephalitis virus, and West Nile encephalitis virus, among others.

yellow fever map

Yellow fever is somewhat unique among the viral hemorrhagic fevers in that the liver is the major target organ. Consequently, the severe form of yellow fever infection is characterized by hemorrhage of the liver and severe jaundice. But, as in infections caused by other virulent viruses, most cases of yellow fever are mild.

Interestingly, the name “yellow fever” does not have its origin in the yellowing of the skin and eyes that is characteristic of severe disease. Instead, it has its origin in the term “yellow jack,” which refers to the yellow flag that was flown in port to warn approaching ships of the presence of infectious disease.

Yellow fever originated in Africa. It is believed to have been brought to the New World by slave ships in the year 1596. As noted above (and discussed below), yellow fever transmission, from an infected individual or primate to an uninfected one, requires a specific vector, the Aedes aegypti mosquito. The sailing ships of the day inadvertently transported the disease across oceans via the mosquito larvae in their water casks.

Before getting to our stories proper, we note a pair of intriguing instances in which yellow fever profoundly affected New World history. In the first of these, yellow fever was a key factor that led Napoleon to sell the Louisiana Territory to the United States in 1803; an act that doubled the size of the United States. It happened as follows. After Napoleon seized power in France, he reinstated slavery in the French colony of Saint Domingue (now Haiti); doing so for the benefit of the French plantation owners there. In response, the rather remarkable Toussaint Breda (later called Toussaint L’Ouverture, and sometimes the “black Napoleon”) led a slave revolt against the plantation owners. In turn, in February 1802, Napoleon dispatched an expeditionary force of about 65,000 men to Haiti to put down the revolt. The rebellious slaves, many fewer in number than the French, cleverly retreated to the hills, believing that the upcoming yellow fever season would wreak havoc on the French force. And, they were correct. By November 1803, the French lost 50,000 of the original 65,000 men to yellow fever and malaria. Thus, in 1804, Napoleon had to allow Haiti to proclaim its independence, and then become the second republic in the Western Hemisphere. Moreover, there is evidence suggesting that Napoleon’s actual purpose in dispatching the expeditionary force was to secure control of France’s North American holdings. With his expeditionary force decimated by yellow fever and malaria, that was no longer possible and, consequently, Napoleon sold France’s North American holdings (the Louisiana Purchase) to the United States.

louisiana purchaseThe Louisiana Purchase, in green.

Second, in 1882, France began its attempt to build a canal across the Isthmus of Panama. However, thousands of French workers succumbed to yellow fever, causing France to abandon the project. The United States was able to successfully take up the task in 1904; thanks to the deeds of the individuals in part I of our story, which now begins.

In May 1900, neither the cause of yellow fever, nor its mode of transmission was known. At that time, U.S. Army surgeon, Major Walter Reed, was appointed president of a U.S. Army medical board assigned to study infectious diseases in Cuba, with particular emphasis on yellow fever. Cuba was then thought to be a major source of yellow fever epidemics in the United States; a belief that was said to have been a factor in the American annexation of Cuba.

ReedMajor Walter Reed

When Reed’s board began its inquiry, a prevailing hypothesis was that yellow fever might be caused by the bacterium Bacillus icteroides. However the board was unable to find any evidence in support of that notion.

Another hypothesis, which was advanced by Cuban physician Dr. Carlos Juan Finlay, suggested that whatever the infectious yellow fever agent might be, transmission to humans requires a vector; specifically, the mosquito now known as Aedes aegypti. Reed was sympathetic to this idea because he noticed that people who ministered to yellow fever patients had no increased risk of contracting the disease, which indicated to Reed that people did not pass yellow fever directly from one to another.

Reed, as president of the medical board, is generally given major credit for unraveling the epidemiology of yellow fever. Yet there were other heroes in this story as well. Finlay, whose advice and experience were invaluable to Reed’s board, was one. He was the object of much ridicule for championing the mosquito hypothesis, at a time when there little evidence that might support it. In any case, Reed, in his journal articles and personal correspondences, gave full credit to Finlay for the mosquito hypothesis.

Acting Assistant Surgeon Major James Carroll was another hero. As a member of Reed’s board, Carroll volunteered to be bitten and, promptly, developed yellow fever. Major Jesse Lazear, also a board member, asked Private William Dean if he might be willing to be bitten. Dean consented, and he too contracted yellow fever. Fortunately, Dean and Carroll each recovered. Not so for Lazear. After allowing himself to be bitten, he died after several days of delirium.

Lazear’s contribution to gaining recognition of the mosquito hypothesis went significantly beyond his tragic martyrdom. When Reed examined Lazear’s notebook after his death, Reed found that it contained several key observations. First, Lazear had carefully documented that in order for a mosquito to be infected; it had to bite a yellow fever patient within the first three days of the patient’s illness. Second, twelve days then had to elapse before the virus could reach high enough levels in the insect’s salivary glands to be transmitted to a new victim.

The observations of the board, up to then, convinced Reed and the others that the mosquito hypothesis indeed was correct. Yet Reed knew that more extensive controlled experiments would be needed to convince the medical community. So, he directly supervised those experiments, which involved twenty-four more volunteers, each of whom may rightly be considered a hero.

Just as Reed benefited from Finlay’s insights, William C. Gorgas, Surgeon General of the U.S. Army, applied the findings of Reed’s board to develop vector control measures to combat urban yellow fever; first in Florida, then in Havana, Cuba, and next in Panama, where those measures enabled the United States to complete the canal in 1914. The last urban yellow fever outbreak in the United States occurred in New Orleans in 1905, and the last in the New World occurred in 1999 in Bolivia.

The vector control strategy works for urban yellow fever because the Aedes aegypti mosquitoes have a very short flight range and, consequently, the female mosquito does not stray far from the source of her blood meal before laying her eggs. Thus, it is only necessary to control the vector population in the immediate vicinity of human habitation. In practice, this is accomplished by draining potential mosquito breeding sites such as swamps and ditches, and destroying water-collecting objects such as discarded tires.

After Reed’s board was disbanded, he made yet another key contribution to the wiping out of yellow fever. The focus of the board had been on the means of yellow fever transmission; not with the infectious agent itself. In 1901, at the suggestion of William Welch, an eminent Johns Hopkins pathologist, Reed and James Carroll (who nearly died of yellow fever after being experimentally infected while in Cuba), asked whether yellow fever might be caused by a filterable virus. Indeed, they found that they could infect volunteers by inoculating them with filtered serum taken from yellow fever patients. What’s more, theirs was the very first demonstration of a human illness being caused by a filterable agent. That is, yellow fever was the first human illness shown to be caused by a virus. [Pasteur developed an attenuated rabies vaccine in 1885, more than a decade before the discovery of viruses. Remarkably, this most brilliant of experimentalists did not recognize that he was dealing with a previously unknown, fundamentally distinct type of infectious agent; the topic of a future posting.]

[Aside: Walter Reed spent the early years of his Army career at different posts in the American west. The Mount Vernon Barracks in Alabama, which served as a prison for captured Apache Native Americans, including Geronimo, was a particularly interesting stop for Reed. Captain Walter Reed, serving as post surgeon in the 1880s, looked after Geronimo and his followers.]

Part II of this posting concerns the development of Max Theiler’s yellow fever vaccine. But first, here is a bit more background.

Vector control measures ended yellow fever epidemics in most, but not all urban centers worldwide. Outbreaks have not occurred in the United States for more than a century. However, jungle yellow fever still persists in areas of Sub-Saharan Africa and, to a lesser extent, in tropical South America. Individuals who are infected in the jungle by wild mosquitoes can then carry the virus to densely populated urban areas, where Aedes aegypti mosquitoes can transmit the virus from one individual to another. [Vector-mediated, human-to-human transmission happens because the level of yellow fever virus in the blood of an infected person becomes high enough for the infected person to transmit the virus to a biting mosquito. In this regard, the yellow fever virus is an exception to the generalization that humans are a “dead end” host for arthropod-borne (arbo) viruses.]

Fortunately, people who live in high risk areas for yellow fever can be protected by vaccination. Indeed, the World Health Organization’s strategy for preventing yellow fever epidemics in high risk areas is, first, to mass immunize the population, and then to routinely immunize infants. [Vaccinated American or European visitors to West Africa or the Amazon need not be concerned about yellow fever. However, the risk to an unvaccinated person of acquiring yellow fever during a two-week stay at the height of the transmission season (July through October), is estimated to be 5%. Individuals wanting to enter or return from countries where yellow fever is endemic may need to show a valid certificate of vaccination. ]

Part II of our story, concerning Max Theiler and the development of the yellow fever vaccine now begins.

Even as late as the 1920s, some reputable bacteriologists remained unconvinced by the earlier findings of Reed and Carroll that yellow fever is caused by a filterable agent. Instead, they persisted in the belief that the illness is caused by a bacterium. The notion of a bacterial etiology for yellow fever was finally put to rest after A. H. Mahaffy in 1927 discovered that the yellow fever agent could be propagated and cause illness in Asian rhesus monkeys. With an experimental animal now at hand, yellow fever workers were able to prove conclusively that the disease is caused by a virus. [Mahaffy drew the virus he used in his experiments from a 28-year-old African man named Asibi, who was mildly sick with yellow fever. That isolate, referred to as the Asibi strain, will play an important role later in this anecdote.]

Regardless of the significance of the discovery that the yellow fever virus could be propagated in rhesus monkeys, Max Theiler had to contend with the fact that these monkeys were quite expensive; especially for a not yet established young investigator. [They cost the then princely sum of about $7.00 apiece.] As for mice, while they could be bred for pennies apiece, other researchers were not able infect them via the usual practice of inoculating them under the skin or in the abdomen. However, Theiler took a cue from Pasteur’s inability to propagate the rabies virus in laboratory rabbits until he put the virus directly into their brains. Thus, in 1929 Theiler attempted to do the same with yellow fever virus in mice.

TheilerlMax Theiler

Theiler’s attempts to infect the mice by intracranial injection were a success. All of the inoculated mice died within several days. Surprisingly, the dead mice did not display the liver or renal pathology characteristic of yellow fever. Instead, the mice appeared to have succumbed to inflammation of their brains. Thus, the yellow fever virus appeared to be neurotropic in mice. Also, Theiler himself contracted yellow fever from one of his inoculated mice. He was fortunate to survive.

A fortuitous result of Theiler’s perilous bout with yellow fever was that he had become immune to the virus, as revealed by the presence of antiviral antibodies in his blood. Importantly, Theiler’s acquired immunity to the virus validated the possibility of developing an attenuated yellow fever vaccine. And, in a sense, Theiler was inadvertently the first recipient of the nascent vaccine he soon would be developing.

Theiler also determined that the virus could be passed from one mouse to another. And, while the virus continued to cause encephalitis in mice, it caused yellow fever when inoculated back into monkeys; quite a unique and striking set of findings. But, and crucially significant, while continued passage of the virus in mice led to its increased virulence in those animals, the virus was concurrently losing its virulence in monkeys. [In 1930, Theiler moved from the Harvard University School of Tropical Medicine to the Rockefeller Foundation’s Division of Biological and Medical Research. The Rockefeller Foundation shared facilities with the Rockefeller Institute (now University); although it was otherwise administratively separate from it.]

Since the mouse-passed virus was becoming attenuated in monkeys, Theiler’s belief in the possibility of generating an attenuated yellow fever vaccine was bearing out. However, because the mouse-passed virus remained neurovirulent in mice, Theiler was reluctant to inoculate that virus into humans. In an attempt to solve this problem, Theiler turned from passing the virus in the brains of live mice and, instead, began passing the virus in mouse tissue cultures.

Theiler carried out seventeen different sets of trials to further attenuate the virus. In the 17th of these, Theiler used the wild Asibi strain, isolated earlier by Mahaffy. Initially, this virus was extremely virulent in monkeys, in which it caused severe liver damage. But, after passing the virus from culture to culture several hundred times, over a period of three years, a flask labeled 17D yielded the virus that was to become the famous 17D yellow fever vaccine.

Theiler never gave a satisfactory accounting for the “D” in the “17D” designation, and for what, if anything became of A, B, and C. Regardless, the genesis of 17D was as follows. Theiler initially took an Asibi sample that had been multiplying in mouse embryo tissue and continued passing it in three separate types of minced chicken embryo cultures. One of these sets contained whole minced chicken embryos, and was designated 17D (WC). A second set contained chick embryo brain only, and was designated 17D (CEB). In the third set, the brains and spinal cords were removed from the otherwise whole chick embryo tissue cultures. This set, alone among all the sets, generated an attenuated virus that did not induce encephalitis when injected directly into monkey brains. Indeed, Theiler removed the central nervous systems from the chicken tissue in this set of cultures, in the express hope of generating just such an attenuated virus. And, by hook or by crook, the virus emerging from that particular set of passages became the vaccine that is now known simply as 17D.

Field tests of Theiler’s yellow fever vaccine were underway in 1937 in Brazil, and were successfully completed by 1940. In 1951 Theiler was awarded the Nobel Prize in Physiology or Medicine for developing the vaccine.

Next, we return to a point noted above, and discussed in two earlier postings. Neither Jonas Salk nor Albert Sabin were awarded Nobel prizes for developing their polio vaccines (1). And, Maurice Hilleman was never awarded a Nobel Prize, despite having developed nearly 40 vaccines, including those for measles, mumps, and rubella (2). Indeed, Max Theiler’s Nobel Prize for the yellow fever vaccine was the only Nobel Prize ever awarded for a vaccine! Why was that so?

Alfred Nobel, in his will, specified that the award for Physiology or Medicine shall be for a discovery per se; not for applied research, irrespective of its benefits to humanity. With that criterion in mind, the Nobel committee may have viewed the contributions of Salk and Sabin as derivative, requiring no additional discovery. [Hilleman’s basic discoveries regarding interferon should have been sufficient to earn him the award (2). The slight to him may have been because the Nobel committee was reluctant to give the award to an “industrial” scientist. Hilleman spent the major part of his career at Merck & Co.]

So, what was there about Theiler’s yellow fever vaccine that might be considered a discovery? Hadn’t Pasteur similarly developed an attenuated Rabies vaccine in 1885?

Perhaps the “discovery” was Theiler’s finding that passage of the Asibi strain of yellow fever virus in chick embryo cultures, which were devoid of nervous system tissue, generated attenuated yellow fever virus that was no longer neurovirulent in mice and monkeys. But, consider the following.

Theiler indeed believed that removing the brains and spinal cords from the chick embryo cultures in which 17D had been serially passed was the reason why the virus lost its neurovirulence. Nevertheless, as a serious scientist he needed to confirm this for himself. So, he repeated the long series of viral passages under the same conditions as before. But, this time, there was no loss of neurovirulence. Thus, a cause and effect relationship, between the absence of the brains and spinal cords from the tissue cultures and the emergence of non-neurovirulent virus, was not confirmed.

So, perhaps the Nobel committee merely paid lip service to the directives in Alfred Nobel’s will. In any case, Theiler’s 17D yellow fever vaccine has had a virtually unblemished safety record, and is regarded as one of the safest and most effective live-attenuated viral vaccines ever developed.

Theiler’s unshared 1951 Nobel award paid him $32,000. At the time, he resided in Hastings-on-Hudson; a village in Westchester County, NY, from which he commuted to the Rockefeller labs. Theiler’s next door neighbor in Hastings-on-Hudson was Alvin Dark, the star shortstop of the New York Giants. Nobel laureate Max Theiler was known to fellow commuters from Hastings-on-Hudson as the man who lives next door to Alvin Dark.

Virus Hunters, by Greer Williams (Alfred A, Knoff, 1960) was my major source for the material on Max Theiler.

1. Jonas Salk and Albert Sabin: One of the Great Rivalries of Medical Science. On the blog.

2. Maurice Hilleman: Unsung Giant of Vaccinology. On the blog.

 

 

 

Jonas Salk and Albert Sabin: One of the Great Rivalries of Medical Science

Paralytic poliomyelitis was one of the world’s most feared diseases during the first half of the 20th century. However, the dread of poliovirus ended abruptly with the advent of the poliovirus vaccines in the 1950s. This posting tells the stories of the key players in the race to develop a polio vaccine. In particular, it features the rivalry between Jonas Salk and Albert Sabin, the two main contenders in the pursuit. While their vaccines together have led to the near disappearance of poliovirus worldwide, neither was recognized by the Nobel committee for his achievement. We begin with some background.

Poliovirus has long been especially interesting to me, both as a virologist and personally as well. The reason is that I was a child and young teenager during the annual polio epidemics of the 1940s and early 1950s, and can vividly remember the panic that set in early every summer of the pre-vaccine days, when the first neighbor or schoolmate was stricken. You were kept home from school and couldn’t even play outside. A visit to a hospital in those times was associated with the pitiful sight of young polio victims in the iron lungs that filled the wards, and even the hallways of hospitals back then.

iron lung

Not even the emergence of AIDS in the early 1980s evoked fear comparable to that brought on by poliomyelitis. Yet despite the dread of poliomyelitis, the disease actually struck many fewer victims than was commonly perceived by the public. The number of poliomyelitis cases in the United States was typically 20,000 to 30,000 per year in the 1940s and 1950s, while influenza still typically kills 40,000 to 50,000 Americans annually. Yet most individuals, then and now seem indifferent to influenza. What’s more, even the 1918 “Spanish Flu” epidemic, which was arguably the most devastating epidemic in human history, did not cause any panic, despite the fact that during the single month of October 1918, it killed 196,000 people in the United States alone! Estimates of the total number killed worldwide by the 1918 Spanish Flu range between 20 million and 50 million.

So, how can we explain the terror brought on by poliomyelitis? It wasn’t simply because poliovirus struck suddenly, without any warning. So did the “Spanish Flu.” Rather, paralytic poliomyelitis mainly struck children, adolescents and young adults. In contrast, influenza mainly threatens the elderly. And, in truth, most parents are far more emotionally invested in their children’s well-being than in that of their parents or themselves. Furthermore, the sight of a child in an iron lung or leg braces (affected legs became atrophied and deformed) was truly heart rending.

The fear evoked by poliomyelitis was permanently ended in the United States and in much of the developed world as well, by the emergence of Salk’s killed polio vaccine in 1955. Sabin’s live attenuated vaccine followed soon after. [Live vaccines generally contain attenuated (weakened) variants of the virulent virus, which can replicate and induce immunity, but which cannot cause disease.] The response of the public to Salk’s vaccine was so great that he was hailed as a “miracle worker.” Nevertheless, and despite the fact that the vaccines created by Salk and Sabin have nearly ridden the world of poliovirus, neither man would ever be recognized by the Nobel committee.

salk Salk’s public acclaim was resented by his colleagues.

Most virologists of the day strongly favored live vaccines over killed ones, based on the belief that only a live vaccine could induce a level of immunity sufficient to protect against a challenge with live virulent virus. Indeed, the effectiveness of live vaccines had been established much earlier by Jenner’s smallpox vaccine (1798) and Pasteur’s rabies vaccine (1885). Jenner’s smallpox vaccine actually contained live cowpox virus, which was similar enough immunologically to variola to protect against smallpox, while not being able to cause smallpox itself. Pasteur’s rabies vaccine contained live rabies virus that was attenuated by passages through rabbit spinal cords. [Adapting the virus to grow in rabbits attenuated its virulence in humans, while not impairing its ability to induce immunity.] So, bearing in mind the well-established precedence of attenuated vaccines, why did Salk seek to develop a killed vaccine?

In 1941, Thomas Francis, one of the great pioneers of medical virology, working at the University of Michigan, developed a killed influenza vaccine. Providentially, in the same year, Jonas Salk (recently graduated from NYU medical school) came to Francis’ laboratory for postgraduate studies. In Francis’ lab, Salk learned his mentor’s methods for producing his killed influenza vaccine and assisted in its field trials.

Salk’s experience in Francis’ laboratory led him to believe in the potential of a killed poliovirus vaccine. And, Salk learned practical procedures from Francis that would be valuable in his pursuit of that objective. These included the use of formaldehyde to kill the virus, the use of adjuvants to enhance the immunogenicity of the killed vaccine, and protocols for conducting field tests.

In contrast to Salk, Sabin firmly believed that a live attenuated vaccine would be vastly superior to a killed one. And, although Salk won the race to produce an actual vaccine, Sabin had been doing polio research well before the younger Salk emerged on the scene. Indeed, Sabin made several important contributions to the field; some of which are discussed below. For now, we mention that in 1936, Sabin and colleague Peter Olitsky demonstrated that poliovirus could be grown in cultured human embryonic nervous tissue. While this might appear to be a key step towards the development of a vaccine, Sabin and Olitsky feared that nervous tissue might cause encephalitis (inflammation of the brain and spinal cord) when injected into humans.

sabinAlbert Sabin, who developed the live polio vaccine.

John Enders, at the Children’s Hospital of Boston, is the next key player in our story. Enders believed that poliovirus should be able to grow in non-nervous tissue, particularly tissue from the alimentary canal, as suggested to him by the amount of the virus that was present in the feces of many patients. So, in 1948, Enders, and colleagues Thomas Weller and Frederick Robbins, succeeded in growing poliovirus in cultured non-nervous tissue, including skin, muscle, and kidney. As a result of Ender’s work, sufficient amounts of poliovirus could now be grown, free from the hazards of nervous tissue, thereby enabling the mass production of a vaccine.

[Aside: Enders, Weller, and Robbins maintained their tissue samples in culture using the roller culture procedure, in which a horizontally positioned bottle is laid on its side and continuously rotated around its cylindrical axis. In comparison to the older process of growing tissues in suspension, the roller culture method enabled the prolonged maintenance of the tissues in an active state and, consequently, the growth of large amounts of virus. For readers who read Renato Dulbecco and the Beginnings of Quantitative Animal Virology (on the blog), note that Dulbecco developed procedures for growing pure cell types as flat adherent monolayer cultures, thereby making possible quantitative plaque assays of animal viruses.]

In 1954, Enders, Weller, and Robbins shared the Nobel Prize in Physiology or Medicine for their contribution described above. What’s more, the Nobel award to Enders, Weller, and Robbins was the only Nobel award ever given in recognition of polio research! Ironically, Ender’s true interests actually lay elsewhere; with measles. He would later develop a measles vaccine. [Enders has been referred to as the “Father of modern vaccinology.”]

The next key player of note in our story is not a person but, rather, a foundation; the “National Foundation for Infantile Paralysis,” which led and financed the crusade against polio in the pre-NIH days of the 1950s. The National Foundation was actually an outgrowth of the Georgia Warm Springs Foundation, a charitable organization founded by Franklin D. Roosevelt, himself crippled by polio. However, after Roosevelt became president of the United States, he was too polarizing a figure (particularly after his “court-packing” scheme in 1937) to head up a philanthropic organization. Consequently, in 1938, Roosevelt announced the formation of the nonpartisan National Foundation for Infantile Paralysis.

roosevelt Photos of Franklin Roosevelt in a wheel chair are rare and were not shown to the public, which was generally unaware that he was paralyzed from the waist down.

[Aside: The National Foundation was initially funded by the contributions of wealthy celebrities who attended Roosevelt’s yearly birthday bashes. At one of these fundraisers, the vaudevillian, Eddie Cantor, jokingly urged the pubic to send dimes directly to the president. And, bearing in mind the fear evoked by polio, the public, perhaps not recognizing the joke, did exactly that, flooding the White House with nearly three million dimes. And so, the slogan “March of Dimes,” for the Foundation’s grass-roots fund-raising campaign, came to be. And, it was not coincidental that a dime (the Roosevelt dime) was issued in 1946 to memorialize the late president.

In 1950, a March of Dimes chapter in Phoenix, Arizona held a “Mother’s March on Polio,” in which volunteers went door-to-door raising money for polio research. People were urged to leave their porch lights on to show that the volunteers would be welcome. The Phoenix initiative soon spread to other locals, and the Mother’s March became a nationwide annual event.]

The role of the National Foundation went beyond merely raising money for research. It also attempted to provide direction to the research, which often placed it at odds with its grantees. This was the case because Harry Weaver, the director of research at the National Foundation, was focused on bringing a vaccine to the public. In contrast, most of the Foundation’s grantees were largely motivated by their desire to understand basic virological issues, such as poliovirus transmission, replication, and dissemination. What’s more, they believed that there was still too much to be known about poliovirus and poliomyelitis before a vaccine might be a realistic possibility.

[Aside: Apropos the sentiment of some poliovirus researchers that there was too much yet to be known before a polio vaccine might be possible, Jenner’s 1798 smallpox vaccine was developed a half century before the germ theory of disease was proposed, and 100 years before the actual discovery of viruses. It was based on the empirical observation that milkmaids seemed to be “resistant” to smallpox; apparently because they had been exposed earlier to cowpox. The initial smallpox vaccine simply contained matter from fresh cowpox lesions on  the hands and arms of a milkmaid. It was then serially passed from one individual to another; a practice eventually ended because of the transmission of other diseases. And, Pasteur’s 1885 rabies vaccine too was developed before viruses were recognized as discrete microbial entities.]

Sabin’s objection to the Foundation’s priority of having a vaccine available as quickly as possible was somewhat more personal. Since a killed vaccine should be more straightforward and, therefore, quicker to develop than an attenuated one (see below), Sabin believed that Weaver’s sense of the urgent need for a vaccine would lead him to favor supporting Salk’s killed vaccine over his attenuated one. Moreover, Sabin felt that he was being shunted aside. And, Since Sabin remained firm in his belief in the superiority of a live vaccine; he also felt that Weaver’s main concern of having a vaccine available as quickly as possible, would compromise the efficacy of the vaccine that would be implemented in the end.

[Aside: Back in the Enders laboratory, Thomas Weller and Frederick Robbins wanted to enter the polio vaccine race. But, Enders viewed the project as boring and routine; a view pertinent to the question of why Salk and Sabin were never recognized by the Nobel Committee. Furthermore, Enders didn’t believe that a killed vaccine could ever provide adequate protection against polio, or that a live vaccine would be possible without years more of research.]

Sabin’s worry that a killed vaccine would be faster to develop than an attenuated one was borne out when, in1953, Salk was preparing to carry out a field-test of his killed vaccine. Yet Sabin and other poliovirus researchers remained inclined to move slowly, placing them in opposition to Harry Weaver’s sense of urgency. Moreover, Sabin and the other polio investigators were also piqued at the National Foundation for promoting Salk’s vaccine to the public and, also, for promoting Salk himself as a miracle worker. The Foundation’s reason for publicizing Salk was to stir up public enthusiasm for its fund raising campaigns. And Salk indeed was becoming the symbol of the miracles of medical research to an admiring public.

In fairness to the polio researchers who dissented with the National Foundation’s single minded emphasis on bringing a vaccine to the public, there were valid reasons for believing that the Foundation might be moving too quickly. So, consider the following excerpts from a letter that Sabin wrote to his rival, Salk: “…this is the first time they (the Foundation) have made a public statement based on work which the investigator has not yet completed or had the opportunity to present…in a scientific journal…Please don’t let them push you to do anything prematurely or to make liters of stuff for Harry Weaver’s field tests until things have been carefully sorted out, assayed, etc., so that you know what the score is before anything is done on a public scale.”

While Sabin’s advice to Salk seems eminently sensible, Sabin had never before shown any inclination to look out for Salk’s interests. So, might Sabin be sending a non-too-subtle warning to Salk that he could either play by the traditions of the scientific community, or face the consequences of playing to the interests of the Foundation? For his part, Salk was well aware of what was happening and he was indeed embarrassed by the adulation of the press; correctly sensing that it was compromising his standing with his colleagues.

[Aside: The media, in the person of the legendary broadcaster, Edward R. Murrow, provided Salk with a notable and very satisfying moment in the public spotlight. During an April, 1955 interview on the CBS television show See it Now, Murrow asked Salk: “Who owns the patent on this vaccine?” To which, Salk replied: “Well, the people, I would say. There is no patent. Could you patent the sun?”

While Salk’s answer to Murrow endeared him even more to the public, some colleagues questioned whether it might have been disingenuous. Both the University of Pittsburgh, where Salk carried out his work, and the National Foundation, which financed it, indeed had been looking into the possibility of patenting Salk’s vaccine. But, when patent attorneys sought to determine if there was a basis for a patent, Salk readily acknowledged that his vaccine was, for the most part, based on tried and true procedures developed by others.

In point of fact, Salk’s critics held him in low esteem largely because there was little about his vaccine that was innovative. Indeed, Sabin once quipped: “You could go into the kitchen and do what he (Salk) did.” But in fairness to Salk, he never claimed that his vaccine was unique. Instead, in the face of much skepticism, his point had always been that a killed vaccine could protect against polio. He persevered and he was right.

Note that Sabin too gave his vaccine to the world gratis.]

By 1954, field tests of Salk’s vaccine went ahead on a massive scale, involving nearly 1.5 million schoolchildren nationwide. The tests were overseen by Thomas Rivers, an eminent virologist who, at the time, was Director of the Rockefeller Institute. Like most virologists, Rivers favored a live vaccine as the ultimate solution to polio. Nevertheless, he believed that the world couldn’t wait ten or more years for an ideal vaccine, when a satisfactory one might be available at present.

With 57,879 cases of poliomyelitis in the United States in 1952, the peak year of the epidemic, Harry Weaver’s sense of the urgent need for a vaccine was widely shared by the public. Unsurprisingly then, the public eagerly supported the 1954 field test of Salk’s vaccine, as indicated by the fact that 95% of the children in the test received all three required vaccinations. [Killed vaccines require multiple doses. That is so because the first dose only primes the immune system. The second or third dose then induces the primed immune system to produce protective antibodies against the virus. Inoculation with a live vaccine resembles a natural infection and, consequently, a single dose is sufficient to induce immunity.]

The field test of Salk’s vaccine was unprecedented in its size. What’s more, it was supported entirely by the National Foundation, which strenuously opposed outside interference from the federal government. In actuality, the Foundation considered federal funding for polio research to be a “Communistic, un-American…scheme.”

[Aside: President Dwight Eisenhower, a Republican and a fiscal conservative, also believed that the federal government had no proper a role in health care. Consequently, Eisenhower took little interest in his Department of Health, Education, and Welfare (HEW). What’s more, Eisenhower’s Secretary of HEW, Oveta Culp Hobby, was even more conservative in that regard than Eisenhower himself. In 1955, after the field trials showed the Salk vaccine to be a success, and with the public clamoring for it, there were insufficient amounts of the vaccine available to meet the public’s demands. Thus, even some Republicans were stunned to learn that the Eisenhower administration had taken no actions whatsoever to watch over production of the vaccine or its distribution, believing that this was in the province of the drug companies. When pressed on this, Mrs. Hobby responded: “I think no one could have foreseen the public demand.”

Not surprisingly, American drug companies lobbied intensely to keep vaccine production under their own control. A different scenario played out in Canada, where the government viewed polio as a national crisis, and took control of its vaccination program, with overwhelming public support.]

All did not go well for Salk and his vaccine after the successful 1954 field tests. In April 1955, more than 200,000 children were inoculated with a stock of improperly inactivated vaccine made by Cutter Laboratories; one of the five companies that produced the vaccine in 1955. [The others were Eli Lilly, Parke-Davis, Wyeth, and Pitman-Moore.] The Cutter vaccine caused 40,000 cases of abortive poliomyelitis (a form of the disease that does not involve the central nervous system), and 56 cases of paralytic poliomyelitis; 5 of which were fatal. What’s more, some of the children inoculated with the Cutter vaccine transmitted the vaccine virus to others, resulting in 113 more cases of paralytic poliomyelitis and 5 fatalities.

A congressional investigation blamed the “Cutter incident” on the NIH Laboratory of Biologics Control, for insufficiently scrutinizing the vaccine producers. In point of fact, the NIH did little testing on its own. Instead, it mainly relied on reports from the National Foundation, whose agenda was to proceed with the vaccinations. Yet the NIH did have an early, in-house warning of potential problems with the Cutter vaccine, which it failed to act on. Bernice Eddy, a staff microbiologist at the NIH, reported to her superiors that the Cutter vaccine caused paralysis when inoculated into monkeys. However, no action was taken in response to Eddy’s warning. [In 1959, Eddy discovered simian virus 40 (SV40) in monkey kidney tissue that was used for vaccine production. By that time, live SV40 had unknowingly been injected into hundreds of millions of people worldwide; perhaps the subject of a future blog posting.]

Salk was exonerated of any fault in the Cutter incident. Moreover, after that episode, not a single case of polio in the United States would be attributed to Salk’s vaccine. Nevertheless, while Salk’s killed vaccine was perfectly safe when properly prepared, the Cutter incident led to the perception that it was unsafe. Consequently, Salk’s killed vaccine was eventually replaced by Sabin’s live attenuated one. Ironically, as we will see, the perception that Salk’s vaccine was dangerous led to its replacement by a more dangerous one.

Sabin’s work on his live polio vaccine began in 1951 and, like Salk; he was supported by the National Foundation. Sabin’s task was more difficult than Salk’s because it is more straightforward to kill poliovirus, than it is to attenuate it. [The attenuated virus must be able to replicate in the digestive tract and induce immunity, yet be unable to damage the nervous system.] But Sabin persisted, sustained by his conviction that a live vaccine would invoke stronger, longer-lasting immunity than a killed vaccine. Sabin attenuated his vaccine by successive passages through monkey tissue, until the live virus could no longer cause paralysis when inoculated directly into chimpanzee spinal cords.

[Aside: At this early date, live-vaccine-proponents could not have known that only a live vaccine could activate T-cell mediated immunity, which is generally necessary to clear a virus infection. Instead, their preference for live vaccines was based on the simpler, but correct notion that inoculation with a live vaccine would more closely approximate a natural infection. Also, since the vaccine virus is alive, vaccinated individuals might transmit it to unvaccinated ones, thereby inducing immunity in the latter as well. On the other hand, the attenuated vaccine poses a deadly threat to individuals with impaired immune systems, such as AIDS patients and individuals on immunosuppressive regimens following organ transplants.]

In 1954, a successful small-scale test of Sabin’s vaccine was carried out, which involved thirty adult human prisoners at a federal detention facility. The promising outcome of this test warranted a larger field-trial of Sabin’s vaccine. But, several obstacles stood in the way. First, the National Foundation was not inclined to support another massive field trial, now that Salk’s vaccine was already in use. Second, the Foundation was still reeling from the Cutter incident, and had no inclination to be caught up in another such debacle. Third, it would be virtually impossible to conduct the trials in the United States, since millions of American children had already been inoculated with Salk’s vaccine. The ensuing course of events was rather remarkable.

By 1956, poliomyelitis had become a serious public health crisis in the former Soviet Union. Consequently, a delegation of Russian scientists came to the United States to meet with Salk and consult with him on how to produce his vaccine. However, the Russians were disposed to meet with other polio researchers as well. Thus, Sabin seized this opportunity to invite the Russians to visit his laboratory at the University of Cincinnati, where he was able to tout his live vaccine to them. Sabin’s pitch was apparently effective, as he secured an invitation from the Russians to visit the Soviet Union, where he spent a month, further hyping his vaccine.

[Aside: While Sabin was in Russia, the Russians requested from him a sample of his live vaccine. So, when Sabin returned to the United States, he sought permission from the State Department to send the Russians the samples they requested. The State Department approved the request; but it did so over objections from the Defense Department, which was concerned that the vaccine virus might have “biological warfare applicability.”]

With the incidence of poliomyelitis on the rise in the Soviet Union, the Soviet Health Ministry needed to quickly decide which vaccine to adopt; Salk’s or Sabin’s. The Russians were already producing the Salk vaccine, but were unable to consistently maintain its efficacy from one batch to another. So, the Soviets invited Salk to visit Russia, so that he might help them to solve the problems they were having producing his vaccine.

Salk then made a decision that he would long regret. Because of pressure from his wife to spend more time with his family, Salk turned down the Russian invitation. The upshot was that the Russians turned instead to Sabin. In 1959 they vaccinated 10 million children with vaccine strains sent to them by Sabin. Soviet results with the Sabin vaccine were so promising that the Soviet Health Ministry decided to then use it to vaccinate everyone under 20 years of age. A total of seventy-seven million Soviet citizens were vaccinated with Sabin’s vaccine, vastly exceeding the number vaccinated during field trials of the Salk vaccine in the United States.

The U.S. Public Health Service did not endorse the Sabin vaccine for use in the United States until 1961. By then, the Salk vaccine had virtually eliminated polio from the country. Nevertheless, Sabin’s vaccine supplanted Salk’s in the United States and in much of the rest of the world as well.

Yet all did not go well with Sabin’s vaccine either. As noted above, after the Cutter incident, there were no cases of poliomyelitis in the United States that could be attributed to Salk’s vaccine. In contrast, Sabin’s vaccine caused about a dozen polio cases per year, a frequency of about one case per million vaccinated individuals. At least some of these cases resulted from the ability of the attenuated virus to revert to a more virulent form. What’s more, reverting viruses posed a threat to non-vaccinated individuals in the population. For instance, in 2000/2001, there were 21 confirmed cases of poliomyelitis in the Dominican Republic and Haiti, which were traced to a single dose of the Sabin vaccine that was administered during the preceding year. [As noted in an above Aside, since the Sabin vaccine is alive, vaccinated individuals might transmit the vaccine virus to unvaccinated individuals.]

In actual fact, the few cases of poliomyelitis that now occur in the West are vaccine-related, resulting from the rare reversions of Sabin’s vaccine. Ironically, the Sabin vaccine, which played a crucial role in the near eradication of polio from the world, had become an obstacle to the complete eradication of the virus. In 2000, the U.S. Centers for Disease Control (CDC) recommended the complete return to the Salk vaccine in the United States. However, the Sabin vaccine would continue to be used in much of the developing world.

[Aside: Several polio hotspots remain in the world. Three major ones are Pakistan, Afghanistan, and Nigeria. Recent outbreaks have also occurred in Syria and Somalia. In each of these instances, social and political climates make it difficult to carry out eradication campaigns.

As recently as March 2014, militants attacked a polio vaccination team in northwest Pakistan, detonating a roadside bomb and then opening fire on their convoy, killing 12 of their security team, and wounding dozens more. Some Pakistani religious leaders denounced the vaccination campaign in Pakistan as a cover for spying or as a plot to sterilize Muslim children.

In the developed world there is a very different problem. Ironically, the great success with which the polio vaccines eradicated the virus in the West has created conditions there in which poliomyelitis might make a most unwelcome return. That has come about because too many parents in the developed world now view polio as ancient history, and have become complacent about having their children vaccinated. What’s more, some parents are heeding unsubstantiated warnings that the risks of vaccines are greater than the risks of the viruses. Consequently, the frequency of vaccinated individuals in the West is declining to the point where the West may be susceptible to outbreaks sparked by imported cases. These issues will be discussed at length in a subsequent posting.]

We turn now to an issue raised at the outset of this posting; neither Salk nor Sabin was recognized by the Nobel Committee for his contribution. That is so, despite the fact that their individual efforts, taken together, have virtually eliminated polio from the world.

Max Theiler, at the Rockefeller Institute, is relevant regarding the Nobel issue, and for several other reasons as well. First, Theiler took an early interest in Sabin’s career during Sabin’s years at the Rockefeller (1935 to 1939). Second, during those years Theiler was working on a live attenuated vaccine for yellow fever. Like most virologists of the day, Theiler believed that only a live vaccine could provoke significant long-lasting immunity. And, Theiler’s thinking on this matter likely influenced Sabin’s later approach to a polio vaccine. Thirdly, and important in the current context, in 1951 Theiler was awarded the Nobel Prize in Physiology or Medicine for his yellow fever vaccine. Fourth, Theiler’s Nobel Prize was the only one ever awarded for the development of a virus vaccine!

Why was Theiler’s Nobel award the only one ever given for the development of a virus vaccine? In addition, recall that John Enders, Thomas Weller, and Frederick Robbins shared the 1954 Nobel Prize for Physiology or Medicine, for demonstrating that poliovirus could be propagated in non-nervous tissue. Moreover, the Nobel Prize shared by Enders, Weller, and Robbins was the only one ever given in recognition of polio research! Why weren’t Salk and Sabin recognized as well? Didn’t they also contribute substantially “to the benefit of mankind;” a standard for the award, as specified by Alfred Nobel?

Apropos these questions, it may be relevant that Alfred Nobel also specified that the prize for physiology or medicine should recognize a “discovery” per se. With that criterion in mind, the Nobel committee may have viewed the contributions of Salk and Sabin as derivative, requiring no additional discovery. In contrast, the discovery of Enders, Weller, and Robbins, refuted the previously held belief that poliovirus could be grown only in nervous tissue; a breakthrough that paved the way to the vaccines.

But then, what was there about Theiler’s yellow fever vaccine that might be considered a discovery? Hadn’t Pasteur developed an attenuated Rabies vaccine in 1885? And, what of Jenner’s earlier 1798 smallpox vaccine, comprised of live cowpox virus?

To the above points, Sven Gard, at the Karolinska Institute, and a member of the Nobel committee for Physiology or Medicine, wrote the following in his evaluation of Theiler’s prior 1948 Nobel nomination: “Theiler can not be said to have been pioneering. He has not enriched the field of virus research with any new and epoch-making methods or presented principally new solutions to the problems, but he has shown an exceptional capacity to grasp the essentials of the observations, his own and others, and with safe intuition follow the path that led to the goal.”

Despite the seeming inconsistency between Gard’s comments and Nobel’s instruction that the prize be awarded for a discovery, Gard nonetheless concluded that Theiler’s contributions indeed merited the Nobel award. [Incidentally, Theiler’s 1948 Nobel nomination was a detailed six-page-long document, written and submitted on his behalf by Albert Sabin!]

To the same point, Hilding Bergstrand, also at the Karolinska Institutet, and chairman of the Nobel Committee for Physiology and Medicine, said the following during his otherwise laudatory speech honoring Theiler at the 1951 Nobel Prize ceremony: “The significance of Max Theiler’s discovery must be considered to be very great from the practical point of view, as effective protection against yellow fever is one condition for the development of the tropical regions—an important problem in an overpopulated world. Dr. Theiler’s discovery does not imply anything fundamentally new, for the idea of inoculation against a disease by the use of a variant of the etiological agent which, though harmless, produces immunity, is more than 150 years old.”

Even Theiler himself agreed that he had not done anything fundamentally new. But then, what might Bergstrand have had in mind when referring to Theiler’s discovery? Perhaps it was Theiler’s finding that passage of the Asibi strain of yellow fever virus in chick embryos, which were devoid of nervous systems, generated viable, non-neurotropic attenuated yellow fever virus. If so, then did that discovery fulfill the condition for the Nobel award, as specified by Alfred Nobel? And, if that is the case, then might this discovery have been what makes Theiler’s contribution more worthy than those of Salk and Sabin in the eyes of the Nobel committee? [A more detailed account of Max Theiler’s yellow fever vaccine, particularly with regard to the “discovery” noted here, can be found in The Struggle Against Yellow Fever: Featuring Walter Reed and Max Theiller, now on the blog.]

The seemingly trivial distinction between the worthiness of Theiler’s contribution from that of Salk and Sabin, suggests that we may need to look elsewhere for answers to why Salk and Sabin were bypassed by the Nobel committee. One reason suggested in the case of Salk is that in the elitist world of big-time science, he had never spent time at a prestigious Research institution like the Rockefeller. Yet he did carry out postgraduate studies in association with the eminent Thomas Francis. So perhaps he was passed over by the Nobel committee because it did not see anything innovative about his vaccine. Or, perhaps it was because he allowed himself to be promoted as a celebrity by the March of Dimes, thereby causing resentment among his colleagues.

But, how then might we explain the case of Sabin? Sabin had not been used by the National Foundation to promote its fund-raising. And, he had done research at the Rockefeller Institute. Moreover, Sabin made seminal contributions to the poliovirus field before and after beginning his vaccine work. As noted above, Sabin and Peter Olitsky demonstrated that poliovirus could be grown in cultured human embryonic nervous tissue. Moreover, Sabin provided experimental evidence that the poliovirus port of entry is the digestive tract, rather than the respiratory tract, as was previously thought. And, Sabin established that the incidence of poliomyelitis tended to be highest in urban populations which had the highest standards of sanitation.

[Aside: Sabin’s finding, that the poliovirus route of entry is via the alimentary tract, validated the premise that poliomyelitis might be prevented by a live oral vaccine. In contrast, Salk’s killed vaccine needed to be injected. An advantage of a vaccine being administered by the oral route, particularly in developing countries, is that trained medical personnel are not required for its administration. On the other hand, the killed vaccine is safer. The few cases of poliomyelitis that now occur in the West are vaccine-related, resulting from rare reversions to virulence of the attenuated virus.]

[Aside: Why was the incidence of poliomyelitis highest in urban populations that had the highest standards of hygiene? Polio infection tends to be milder in the very young, perhaps because they are partially protected by maternal antibodies. But, in areas with high standards of hygiene, infection tends to occur later in life, when maternal antibodies have waned, and the infection can then be more severe.

Before this was appreciated, poliomyelitis was thought to originate in the slums and tenements of cities, and then spread to the cleaner middle-class neighborhoods. Thus, during polio outbreaks in New York City, there were instances when slums and tenements were quarantined, and city dwellers fled to the suburbs, all to no avail.]

Were Sabin’s discoveries noted above, taken together with his vaccine, worthy of a Nobel Prize? In any case, Sabin indeed had been nominated for the Nobel award by numerous colleagues, including Enders. So, why was Sabin never awarded the Nobel Prize? Perhaps the Nobel committee could not recognize Sabin without also recognizing Salk, which it may have been reluctant to do for reasons noted above. Or, as has been suggested, the continual back-and-forth carping between supporters of Salk and Sabin may ultimately have diminished enthusiasm in Stockholm for both of them.

Salk (in 1956) and Sabin (in 1965) each received the prestigious Lasker Award for Clinical Research (often seen as a prelude to the Nobel) and, earlier, in 1951, Sabin was elected to the U.S. National Academy of Sciences. In contrast, Salk was the only prominent polio researcher not elected to the Academy. And regarding the Nobel Prize, Salk once joked that he didn’t need it, since most people thought he had already won it.

In 1963 Salk founded the prestigious Salk Institute for Biological Studies in La Jolla, California. Francis Crick (1), Renato Dulbecco (2), and Leo Szilard (3), each of whom is featured elsewhere on the blog, were among the eminent scientists recruited by Salk to the La Jolla campus. Bearing in mind Salk’s alienation from other medical researchers of the day, we might enjoy his remark “I couldn’t possibly have become a member of this institute if I hadn’t founded it myself.” Jonas Salk died of congestive heart failure in 1995 at the age of 80. He remains one of the most venerated medical scientists ever.

salk instSalk Institute for Biological Studies

[Aside: Salk married Dora Lindsay in 1939, right after he graduated from NYU medical school. But, the marriage eventually fell apart, and the couple divorced in 1968.

In 1970, Salk married the artist Francois Gilot, who had been the mistress of Pablo Picasso for nearly ten years and with whom she had two children. Salk and Gilot met in 1969, at the home of a mutual friend in Los Angeles. They remained married until Salk’s death in 1995.

The following is from an April 27, 2012 article in Vogue by Dodie Kazanjian, entitled Life after Picasso: Francois Gilot.

“On a trip to Los Angeles in 1969, a friend introduced her to Jonas Salk. She had no interest in meeting him—she thought scientists were boring. But soon afterward, he came to New York and invited her to have tea at Rumplemayer’s. ‘He didn’t have tea; he ordered pistachio and tangerine ice cream,’ she recalls. ‘I thought, Well, a scientist who orders pistachio and tangerine ice cream at five o’clock in the afternoon is not like everybody else!’ He pursued her to Paris and a few months later asked her to marry him. She balked. “I said, ‘I just don’t need to be married,’ and he said, ‘In my position, I cannot not be married.’ He gave me two pieces of paper and told me to write down the reasons why I didn’t want to get married.” She complied. Her list included: ‘I can’t live more than six months with one person’; ‘I have my own children’; ‘I have my career as a painter and have to go here and there’; ‘I’m not always in the mood to talk. Et cetera, et cetera, et cetera.’

Salk looked at the list and said he found it ‘quite congenial.’ They were married in 1970 and were together until he died in 1995. ‘It worked very well,’ she says, because after all we got along very well.’”]

Albert Sabin became president of the prestigious Weizmann Institute of Science in Israel, but stepped down in November 1972 for health reasons. He passed away in 1993 at the age of 86. Unlike in the case of Salk, and despite the fact that he never was awarded the Nobel Prize, Sabin’s standing among his colleagues always remained high.

Before concluding, we note two other important contenders in the quest for a polio vaccine. The first of these was Isabel Morgan, the daughter of the great geneticist, Thomas Hunt Morgan. Isabel Morgan nearly produced a killed polio vaccine before Salk succeeded in doing so. Working at Johns Hopkins, she generated formalin-inactivated poliovirus preparations that indeed protected monkeys against intracerebral injections of live poliovirus. However, Morgan gave up her research in 1949 to marry and raise a family. At that time, Salk had barely begun his work. But, if Morgan had remained in the race, Salk may yet have beaten her to the finish line, since she was reluctant to test her vaccine on human subjects.

Hilary Koprowski was the other noteworthy contender in the race to a polio vaccine. Koprowski was a Polish Jew who immigrated to Brazil in 1939, after Germany invaded Poland. He later came to the United States, where, in 1945, he was hired by Lederle Laboratories to work on a project to develop a live polio vaccine. Koprowski’s foray into polio had a few interesting happenings. Moreover, he went on to have a renowned career as a virologist. Thus, we discuss him in a bit more detail.

[Aside: Salk and Sabin also were Jewish. And Sabin too was born in Poland. In 1921 he immigrated with his family to the United States, at least partly to escape persecution of Jews in his birth-land.]

Koprowski began his work at Lederle before John Enders developed methods for growing poliovirus in monkey kidney cell cultures. Consequently, Koprowski attenuated his live vaccine by passaging it in mouse brains in vivo. In 1950, several years before Sabin’s vaccine was ready for testing, Koprowski found that his vaccine indeed protected chimpanzees from challenge with virulent poliovirus. Koprowski then tested his live vaccine in humans; first on himself, and then on 19 children at a New York State home for “feeble minded” children.

Koprowski was still an unknown figure in the scientific community when he made the first public presentation his test findings. This happened at a 1951 National Foundation roundtable that was attended by the major polio researchers of the day, including Salk and Sabin. The conferees were aghast upon hearing that Koprowski had actually tested his live vaccine, grown in animal nerve tissue, on children. Koprowski’s response was simply that someone had to take that step. Also, it didn’t help Koprowski’s standing with his academic colleagues that he was employed by Lederle. In those pre-biotech days, he was looked down on as a “commercial scientist.”

Human testing was of course a necessary step in the development of this or any human vaccine. What’s more, using cognitively disabled children as test subjects was a common practice back then. So, the actual concern of Koprowski’s colleagues was that he inoculated human subjects with a vaccine that was grown in animal brains. Koprowski also may have been treading on shaky legal ground, since it is not clear whether he ever obtained consent from the children’s parents.

[Aside: The only guidelines for such tests back then were the so-called Nuremburg Code of 1947, which was formulated in response to Nazi “medical” experiments. Informed consent was one of the Nuremburg guidelines, which, in the case of children, meant consent from a parent or guardian. Note that federal approval was not required to test vaccines or drugs in those days.]

Irrespective of whatever uproar Koprowski caused by testing his vaccine on helpless institutionalized children, he indeed had a live polio vaccine in 1949; several years before Salk and Sabin brought out their vaccines. However, Koprowski’s vaccine began its demise soon afterwards. A small field trial in Belfast showed that the attenuated virus could revert to a virulent form after inoculation into humans. But, bearing in mind that there was not yet any alternative to his vaccine, Koprowski firmly believed that the greater risks of natural poliovirus infections justified its use.

The fate of Koprowski’s vaccine was sealed in 1960, when the U.S. Surgeon General approved the Sabin vaccine for trial manufacture in the United States, while rejecting Koprowski’s vaccine on safety grounds. Tests showed that Sabin’s vaccine was the less neurovirulent of the two vaccines in monkeys. Sabin had carefully tested plaque-isolated clones of his attenuated viral populations for neurovirulence in monkeys, and he then assembled his vaccine from the least neurovirulent of these clones. Moreover, by this time millions of children in the Soviet Union had had been successfully immunized with the Sabin vaccine.

Koprowski left Lederle Laboratories in 1957 after clashing with its management. After that, he became Director of the Wister Institute in Philadelphia. He then transformed the then moribund Wistar into a first class research organization.

The relationship between Koprowski and Sabin was quite adversarial at the time their vaccines were in competition, but they later became friends. In 1976, Koprowski was elected to the U.S. National Academy of Sciences, an honor shared with Sabin, bit never afforded to Salk.

Here is one last bit on Koprowski. Recall that early lots of the Salk and the Sabin vaccines unknowingly contained live SV40, which had been injected into hundreds millions of people worldwide. While the unknown presence of a live tumor virus in a vaccine must be one of a vaccinologist’s worst nightmares, this finding did not attract the attention of the public. In contrast, a 1992 article in Rolling Stone, which attributed the emergence of HIV to Koprowski’s polio vaccine, created a sensation. The premise of the article was that Koprowski’s vaccine was produced in chimpanzee cells that were contaminated with simian immunodeficiency virus (SIV), which then mutated into HIV when inoculated into humans. As might be expected, there was no evidence to support that premise. Indeed, PCR analysis could not detect SIV or HIV in the supposedly contaminated vaccine lots, and records from Koprowski’s laboratory showed that his vaccine was never grown in chimpanzee cells. So, faced with the possibility of a lawsuit, Rolling Stone issued a retraction.

Readers, who enjoyed the above account of the rivalry between Jonas Salk and Albert Sabin, may also enjoy the account of the rivalry between Robert Gallo and Luc Montagnier in Who Discovered HIV? More on the same topic can be found in How the Human Immunodeficiency Virus (HIV) Got its Name. For a very different kind of rivalry, that between Howard Temin and David Baltimore, see Howard Temin: In From the Cold.

1. Howard Temin: “In from the Cold” On the blog.

2. Renato Dulbecco and the Beginnings of Quantitative Animal Virology On the blog.

3. Max Delbruck, Lisa Meitner, Niels Bohr, and the Nazis On the blog.