Viruses infect all classes of cellular organisms. Those that infect bacteria are called bacteriophages, or phages for short. Some phages are referred to as “lytic,” since they cause the infected bacterium to lyse. In fact, the bacteriolytic effect of these phages actually led to their discovery by Frederick W. Twort in 1915, in London. Felix d’Herelle, made the discovery independently in 1917, in Paris, after he too observed bacterial lysis.
Twort noted that his “bacteriolytic agent” exhibited two of the defining properties of viruses; the ability to pass through filters that block bacteria, and the requirement for cells (bacteria in that instance) in order to proliferate. Nevertheless, whereas Twort considered the possibility that his bacteriolytic agent might be a virus, he seemed to favor the notion that it was an enzyme secreted by the bacteria.
In contrast to Twort, d’Herelle was quite certain that the phenomenon he observed was due to a virus; one able to infect bacteria. Moreover, unlike Twort, d”Herelle ardently followed up his initial observations. d’Herelle also gave bacteriophages their name; which means “bacteria eaters,” although this is not what actually happens. See Aside 1.
[Aside 1: As has happened in other instances—e.g., the discovery of HIV (1)—priority for a scientific discovery can be a matter of bitter dispute. In the case of Twort and d’Herelle, contention over priority for the discovery of bacteriophages eventually waned, as many in the scientific community came to accept that their discoveries were independent. However, the observable effect of lytic phages was reported even earlier, in 1896, by British bacteriologist Ernest Hankin, who found that an agent which lyses Vibrio cholerae can pass through filters. Two years later, the Russian bacteriologist Gamaleya noted a similar occurrence in Bacillus subtilis. Yet neither of these researchers pursued the phenomenon, which lay dormant until resurrected by Twort in 1915.]
d’Herelle’s 1917 report of his discovery contains several notable observations (2). First, he stated that the bactericidal microbe cannot be seen under his microscope: “From the feces of several patients convalescing from infection with the dysentery bacillus, as well as from the urine of another patient, I have isolated an invisible microbe endowed with an antagonistic property against the bacillus of Shiga.”
Next, d’Herelle noted that the invisible microbe can be isolated from patients only when the Shiga bacillus is present as well: “In convalescent cases…the antagonistic microbe disappears very soon after the disappearance of the pathogenic bacillus…I have never found this antagonistic microbe in…normal subjects.”
d’Herelle then asserted that the antagonistic effect of the antibacterial microbe is seen only in association with the Shiga bacillus. That is, the agent is host-specific: “I have never obtained an activity against other microbes: typhus and paratyphoid bacilli, staphylococci, and so on.”
d’Herelle went on to proclaim that the agent is indeed a “living germ.” That is, it can proliferate. Moreover, its proliferation requires the presence of the Shiga bacillus: “The antagonistic microbe can never be cultivated in media in the absence of the dysentery bacillus…This indicates that the antagonistic dysentery microbe is an obligate bacteriophage.” Note that this is the first known use of the term “bacteriophage.”
d’Herelle concluded his 1917 paper with a comment on the generality of his findings: “It is probable that the phenomenon is not restricted to dysentery, but that it is of general significance, because I have been able to observe a similar situation, even though weaker, in two cases of paratyphoid fever.” See Aside 2.
[Aside 2: Bear in mind how little was known about viruses in 1917, other than that they pass through filters that block bacteria, and that they require cells to proliferate. Our last posting featured the crystallization of tobacco mosaic virus by Wendell Stanley (3). In Stanley’s 1946 Nobel lecture, he recounted that when he began that project in 1932, “the true nature of viruses was a complete mystery. It was not known whether they were inorganic, carbohydrate, hydrocarbon, lipid, protein or organismal in nature.”]
d’Herelle’s next goal, which he pursued with a passion, was to develop therapies against bacterial infections that would be based on using bacteriolytic phages. He achieved his first success in 1919, when he stopped a typhoid plague in chickens, by means of a phage isolated from a fecal sample of a typhoid-infected chicken.
Later in that same year, d’Herelle attempted phage therapy for the first time in a human; a 12-year-old boy suffering from dysentery at the Hôpital des Enfants-Malades in Paris. d’Herelle successfully treated his young patient with a phage isolated from a fecal sample of another dysentery patient. He ingested the phage preparation himself, to test its safety, before administering it to the boy. Soon afterwards, he cured three additional dysentery patients, using the same phage preparation.
Phage therapy was soon booming, with thousands more successes being claimed. Remarkably, these successes were achieved despite the fact that neither d’Herelle, nor anyone else at the time, knew the actual nature of bacteriophages. See Aside 2 above, and Aside 3.
[Aside 3: The 1925 Pulitzer Prize-winning novel, Arrowsmith, by Sinclair Lewis, describes fictional efforts to develop phage therapy. I highly recommend it, if for no other reason than to get a glimpse of what it was like to do medical research in that earlier time. Interestingly, the idea for Arrowsmith was suggested to author Sinclair Lewis by his friend Paul de Kruif, then a scientist at the Rockefeller Institute, and later a well-known science writer, perhaps best known for his 1926 book, The Microbe Hunters.]
Some of the successes claimed by d’Herelle occurred in 1920 in Indochina, where he used phages from plague-infected rats to treat human plague patients. In 1927, in India, under the sponsorship of the British colonial government, he stopped a cholera epidemic by means of two procedures. In the first, he administered phage preparations directly to individual recipients. In the second, he seeded the wells of cholera-stricken villages with the phages. In both instances the phages were isolated from Indian cholera victims, and in both instances it was claimed that the epidemic was ended within 48 hours, whereas the conventional intervention procedures of day were said to achieve the same result only after 26 days.
Yet despite the thousands of successes claimed by d’Herelle and his adherents, many in the scientific community questioned the efficacy of phage therapy. A major reason was that d’Herelle’s clinical trials did not meet accepted standards of experimental rigor. Most importantly, he did not include appropriate placebo controls in those studies. Perhaps he did not want to deprive any of his subjects of the benefit of the treatment that he so strongly believed in. Yet he also failed to include placebo controls in his earlier studies in chickens.
Nonetheless, in the pre-antibiotic era, there were few alternative interventions against bacterial infection, other than vaccination (where apt) and raising standards of public hygiene. Consequently, many large drug firms, including American companies Eli Lilly, Parke-Davis, Abbott, and Squibb, produced phages to treat a variety of bacterial pathogens. d’Herelle himself founded a commercial laboratory in Paris to produce therapeutic phage stocks. He returned the profits from his commercial venture into the support his phage research.
Notwithstanding the often spectacular successes that could reasonably be attributed to phage therapy, it was not a panacea. For instance, the outcome of phage therapy could be inconsistent, in part because companies were producing phage stocks at a time when these agents were far from understood. Also, phages are highly host-specific. Thus, effective phage therapy depended on accurately identifying the infecting pathogen.
Interest in phage therapy waned in the United States and in Western Europe in the late 1940s. The major reason was the sudden availability of penicillin and other antibiotics, which were easier to use than phages—they could be effective even when the identity of the etiologic agent was not known—and they were more reliable as well. During the Second World War, supplies of penicillin were limited, and priority was given to the military. But, when the war ended in 1945, and the general public became aware of the new “miracle drug,” demand for it was huge and phage therapy quickly fell by the wayside.
But while antibiotics became readily available in the United States and in Western Europe after World War II, this was not the case in Eastern Europe and in the former Soviet Union, which were isolated from Western advances in antibiotic production. Consequently, interest in phage therapy remained high in the East after the war. In fact, hundreds of scientific papers concerning phage therapy were being published in Eastern Europe and in the former Soviet Union. Many of these papers were from the Eliava Institute in Tbilisi, in the former Soviet Republic of Georgia (see Aside 4). The Eliava Institute produced phages against numerous bacterial pathogens, including staphylococci, Pseudomonas, Proteus, and Shigella.
[Aside 4: Georgian microbiologist, Giorgi Eliava, met d’Herelle, and acquired his enthusiasm for phage therapy, while carrying out research at the Pasteur Institute in Paris between 1918 and 1921. In 1923, after Eliava returned to Georgia, he established a laboratory in Tbilisi (renamed the Eliava Institute in 1988) for the explicit purpose of researching phage therapy. In1937 Eliava invited d’Herelle to join him in Tbilisi, where the two might then collaborate. d’Herelle accepted, and after spending several months in Tbilisi, he decided to stay permanently. But, Eliava was arrested by the Soviet secret police and executed as a “People’s Enemy.” One version of events has it that Eliava was executed because he was a rival of the Soviet secret police chief, Lavrenti Beria, for the affection of a woman. d’Herelle fled from Georgia for his own life.]
The Hirszfeld Institute of Immunology and Experimental Therapy, in Wroclaw, Poland, is another Eastern European organization actively engaged in phage therapy research. Work at the Institute has largely been motivated by “the emergence of bacterial strains, which are highly resistant to virtually all available antimicrobial agents.” That quoted phrase, as well as the following, is from the Institute’s web site: “Since 1980 the specific bacteriophages have been used in our Laboratory for the treatment of over 1500 patients with suppurative (i.e. pus producing) bacterial infections, in which a routine antibiotic therapy failed. The results obtained so far showed that phage therapy is safe and highly effective (the majority of patients were cured).” See Aside 5.
[Aside 5: The Hirszfeld Institute was founded by Ludwik Hirszfeld, perhaps best known as one of the co-discoverers of the inheritance of ABO blood type. Hirszfeld was Jewish by birth, but converted to Catholicism. Nevertheless, in 1939 the Nazis removed him from his scientific posts and banished him to the Warsaw Ghetto, where he organized underground anti-epidemic measures and vaccination campaigns against typhus, and also taught secret medical classes. In 1943, a day before he was to be sent from the Ghetto to an extermination camp, he and his wife escaped and found refuge in small Polish villages, using false names. Hirszfeld resumed his scientific career after the war. Incidentally, during the war, d’Herelle was kept under house arrest by the German occupiers of Vichy, France.]
Although enthusiasm for phage therapy has remained high in Eastern Europe and in the former Soviet Union, enthusiasm there did not forestall the declining interest in phage therapy in the West. The Eastern European studies were published in Russian and, as a result, were largely unavailable to scientists in the West. Moreover, those studies often did not meet Western standards of scientific rigor, as they often lacked proper controls and they did not adequately describe experimental procedures. [See reference 4 for a detailed review and assessment of the Eastern European phage therapy trials.]
The standing of phage therapy in the West was also undermined by d’Herelle himself, who hurt his cause by vigorously advocating his abiding belief that natural recovery from bacterial infection results from the bacteriolytic action of phages. He based this assertion on his early finding that he could isolate lytic phages only from those patients who were convalescing from a bacterial infection (see above and reference 2). He also believed that long-lasting immunity is the result of the phages present in the recovered patient.
d’Herelle’s assertions concerning recovery from infection and acquired immunity were at odds with key discoveries then being made by pioneering immunologists, such as Nobel laureates Elie Metchnikoff and Paul Ehrlich, who demonstrated the importance of leukocyte recruitment and phagocytosis in recovery from bacterial infection. But d’Herelle continued to assert that neither phagocytosis nor antibodies could produce bacteriolysis, which he thought was necessary to completely destroy the bacteria. The scientific community responded to d’Herelle’s heresy as though support for phage therapy implied lack of support for key developments in immunology, serology, and vaccines.
Yet despite the scientific and social reasons for the decline of phage therapy in the West, phage therapy may yet undergo a resurgence here because of the ever increasing threat of antibiotic-resistant bacteria. For instance, the European Commission is now funding a research project, called “Phagoburn,” which involves collaboration between France, Belgium, and Switzerland, with the goal of evaluating phage therapy for the treatment of burn wounds infected with Escherichia coli and Pseudomonas aeruginosa.
Patients in the Phagoburn study will receive phage preparations made by the French company, Pherecydes Pharma, which now has more than 1,000 bactericidal phages in its collection. And while researchers in the West are eagerly awaiting results of Phagoburn, some EU citizens, who are suffering with antibiotic-resistant infections, have travelled to Georgia, to receive phage therapy there.
In March, 2014, the U.S. National Institute of Allergy and Infectious Diseases included phage therapy among the seven approaches it was considering to counter antibiotic resistance. Yet it remains to be seen whether American drug companies will invest in phage therapy. They might be hesitant because of a 2013 U.S. Supreme Court ruling that prevents patenting natural genes; a ruling that might also apply to phages isolated from nature. Obtaining a patent might also be impeded by the fact that the principle of phage therapy is now nearly a century old. What’s more, after the research, development, and patenting phases, the company must still secure approval from the U.S. Food and Drug Administration to treat humans with a self-replicating agent that has the ability to evolve.
Before moving on, somewhat more might be said regarding the promise of phage therapy in the era of antibiotic resistance. First, as stated above, the specificity of a phage for a particular host bacterium can be a disadvantage since; as a result, effective phage therapy requires accurate identification of the infecting pathogen. However, the host-specificity of phage therapy nonetheless provides a significant advantage, relative to broad-spectrum antibiotics. Phage therapy selects for resistant bacteria only among the targeted bacteria, while antibiotics select for resistant mutants of many bacterial species; not just for resistant mutants of the targeted bacteria. And, if a particular bacterium should become resistant to a particular phage, it is very much easier, and less expensive, to produce a new generation of phage mutants able to attack the phage-resistant bacterium than it is to develop new antibiotics to attack multi-drug resistant bacteria. Furthermore, antibiotics target the normal body flora, as well as infecting pathogens. Thus, antibiotics, but not therapeutic phages, may affect the overall microbial balance in a patient, which in turn may lead to serious opportunistic infections.
Interestingly, a 1945 paper in The Lancet, by F. Himmelweit, who was working at St. Mary’s Hospital in London (where penicillin was first discovered), reported that the combination of antibiotics and phage therapy gave positive outcomes in clinical trials, while greatly reducing the occurrence of penicillin-resistant bacteria. Yet this finding seems to have been completely ignored in the West, despite the fact that penicillin-resistant bacteria were emerging as soon as penicillin was put into practice.
Irrespective of the future of phage therapy in the West, Felix d’Herelle’s legacy would seem to be secure. In addition to pioneering phage therapy, he also firmed up the discovery of bacteriophages, and he was also the first to develop the plaque assay method for titrating and purifying a phage (2). Taken together, these additional achievements provided the foundation for the origin of molecular biology (5).
Remarkably, d’Herelle had only a high school education and he was self-taught in science. Yet in 1928, in recognition of his development of phage therapy, he was offered a tenured professorship by Yale Medical School, which he accepted. Earlier, in 1924, he received an honorary medical degree from the University of Leiden, as well as the Leeuwenhoek medal from the Royal Netherlands Academy of Arts and Sciences. The latter award is notable, since it is granted only once every ten years to the scientist deemed to have made the most significant contribution to microbiology during the preceding decade. It was especially meaningful to d’Herelle, since his idol, Louis Pasteur, received the same award in 1895.
In the 1960s d’Hérelle’s name appeared on a Nobel Foundation list of scientists who were deemed worthy of the Nobel Prize, but who did not receive it for one reason or another. d’Herelle is believed to have been nominated eight times for the Nobel award. So it is also remarkable that when d’Herelle died in Paris in 1949, he was virtually a forgotten man.
References:
1. Who Discovered HIV?, Posted on the blog January 23, 2014.
2. D’Herelle, F. (1917) Sur un microbe invisible antagoniste des bacilles dysenteriques (An invisible microbe that is antagonistic to the dysentery bacillus). Comptes rendus Acad. Sciences 165:373-375. [The English translation, here and above, appears in Thomas Brock’s Milestones in Microbiology, Prentice-Hall, 1961.]
3. Wendell Stanley: First to Crystallize a Virus, Posted on the blog April 23, 2015.4.
4. Sulakvelidze, A., Z. Alavidze, and J. G. Morris, Jr. (2001) Bacteriophage Therapy. Antimicrob Agents Chemother. 45: 649–659.
5. Norkin, Leonard C. (2010) Virology: Molecular Biology and Pathogenesis. ASM Press, Washington, D.C. See Chapter 1.
Leonard Norkin Virology Site 