CALMETTE TAKES UP THE CAUSE
Others were certainly ambitious to succeed where Koch had failed. Hope was raised that protection against tuberculosis could be found following the success of the German microbiologist Emil von Behring’s work on diphtheria and the development of a vaccine for typhoid by Sir Almroth Wright in England in 1897. One of the researchers who decided to take on the tuberculosis challenge was the French physician and bacteriologist Léon Charles Albert Calmette.
Born in Nice in 1863, Albert Calmette, the son of a lawyer, wanted a career in the navy and became a cadet at the naval academy in Brest. After contracting typhoid fever he had to put his ambition on hold until 1881, when he was accepted for training as a naval physician at the School of Naval Physicians in Brest. Even as a student Calmette was keen to be involved in research projects and early in his career he developed an atomiser for spraying antiseptic solutions.
Calmette’s first post as a member of the Naval Medical Corps was to Hong Kong in 1883, where he met Patrick Manson, a Scottish parasitologist and founder of the London School of Tropical Medicine, whose malarial studies Calmette translated into French.[22] After Hong Kong, Calmette spent some years in West Africa investigating malaria and sleeping sickness (both of which Robert Koch would work on twenty years later) and then went to Newfoundland. In 1890 Calmette was transferred to the newly formed French Colonial Medical Service and he asked for leave to study at the Pasteur Institute in Paris. Here the young scientist worked under the supervision of Emile Roux but was also noticed by Pasteur, who recognised Calmette’s potential and in 1891 nominated him for the job of organising the Saigon branch of the Pasteur Institute in what was then French Indochina. Calmette devoted himself to this task and soon after his arrival in the colony began producing smallpox and rabies vaccines. Like Pasteur and Koch, Calmette was able to keep many research balls in the air at one time. While in Vietnam he also undertook an extensive study of snake venoms and plant and bee poison and successfully developed a number of snake anti-venom serums.
Having an extensive knowledge of disease does not necessarily confer immunity and after two years in Saigon Calmette contracted a severe form of dysentery which forced him to return to France. His position at the Saigon institute was taken over by Alexandre Yersin whom Calmette had convinced to join the French Colonial Medical Service. Yersin, a Swiss biologist, had previously been involved in the development of the rabies vaccine after joining Pasteur’s research team in 1886, and in 1894 he would lead the French mission to Hong Kong and discover the cause of bubonic plague. There were many foes to conquer.
In Paris, when he was sufficiently recovered Calmette was given a part-time administrative post at the Ministry of the Colonies and spent part of his mornings and evenings in Roux’s laboratory at the Pasteur Institute. In 1894, Louis Pasteur was asked by the city of Lille, where he had started his career in bacteriology, to establish a branch of the Pasteur Institute there.[23] Roux suggested Calmette for the director’s position, a role that he fulfilled until 1919. Under Calmette’s leadership the institute became prestigious.
While the Lille institute was being built, Calmette, a gifted organiser, started work in temporary laboratories which within a short time were producing sufficient smallpox and rabies vaccine to meet the needs of northern France. Also a talented inventor, Calmette developed a new commercial process for the conversion of starch into sugar and alcohol, the proceeds from which he would use to help finance a new project he was planning. After moving into the new building and ensuring that vaccine production was in full swing, Calmette turned his attention to the next major assault on tuberculosis.
Calmette’s research followed Pasteur’s practice of developing attenuated live vaccines. To do this he needed a veterinarian to maintain the stock of experimental animals. Professor Nocard, the veterinarian and microbiologist at the Pasteur Institute who had helped Pasteur and Roux in their classic anthrax experiments, recommended his assistant Camille Guérin, who joined Calmette in Lille in 1897.[24] Thus began a long association that would lead to the discovery and development of the successful tuberculosis vaccine, bacille de Calmette et Guérin (BCG). Camille Guérin, who had been born in Paris in 1872, spent most of his professional life at the Pasteur Institute in Lille, and later in Paris, where he continued to supervise the production of BCG after Calmette’s death in 1933.
The research into tuberculosis was postponed for a year in 1899 when Calmette was sent to Portugal to help stem an epidemic of bubonic plague. A year was not a long time, however, because the research carried out by Calmette and Guérin was grindingly slow. By 1906 Guérin had demonstrated that resistance against tuberculosis is associated with the presence of living tubercle bacilli in the blood and two years later in 1908, after experimenting with different culture mediums, Calmette and Guérin had succeeded in obtaining an attenuated strain of the bovine tubercle bacillus.
The culture medium they used consisted of potato, glycerine and bile salts. The addition of ox bile to the mix, which may have been the result of trial and error, was to prove critical. The idea may also have come from a Norwegian physician Kristian Feyer Andvord, who was an expert on tuberculosis.[25] (In a lecture in 1991 on the 100th anniversary of the Veterinary Institute in Oslo in Norway, the chief physician, Gunnar Bjune, said that the idea of producing successively less virulent tubercle bacilli on a medium to which ox bile was added was suggested to Calmette in a discussion he had with Andvord in Paris.) Wherever the idea came from, Calmette and Guérin found ox bile was an effective agent for breaking up the clumps of bacilli and also changed the virulence and morphology, i.e. the form and structure of the organisms.
Prolonged culture of the bacilli in media containing bile did indeed produce a strain of organisms from which a safe and effective vaccine could be made. Calmette and Guérin had made great strides. Small doses of bovine bacilli injected into cattle produced accumulations of bacilli in parts of the abdomen but did not cause the disease. In December 1908 Calmette informed the French Academy of Sciences of this discovery. Over the next thirteen years, from 1908 to 1921, Calmette and Guérin conducted a series of historic experiments. Using a bovine strain of tubercle that had been isolated by Nocard in 1902, they sub-cultured the organisms a staggering 231 times, producing ever less virulent bacilli.
Totally committed to their goal, the two scientists took grave risks when they continued their work after Lille was occupied by the German army during World War I. Their research cattle were requisitioned by the Germans, putting an end to most of the animal experiments. Calmette secretly kept some pigeons but this was not the only regulation he flouted. The occupying authorities lost patience with Calmette and he was interned. His situation became even more tenuous when his wife was taken to Germany as a hostage and he was put under the threat of a death sentence. But Calmette was destined for greater things. A prominent German bacteriologist, Richard Pfeiffer, who was a general in the medical division of the German army, admired Calmette. Respect for a fellow scientist transcended national boundaries and Pfeiffer intervened on Calmette’s behalf.
During the war, in 1917, Elie Metchnikov, who followed Pasteur as Director of the Pasteur Institute, died. Calmette was named Associate Director, in absentia, a great honour and a symbol of his standing in the scientific community. Despite the risks he took, Calmette survived and after the war ended in 1918 was free to go to Paris to devote himself completely to a cure for tuberculosis.
Working together again, Calmette and Guérin picked up the pieces of their research but it was some years before they could prove conclusively that the vaccine they had developed was safe for humans. The first prophylactic test of BCG on a human was carried out in 1921 when a physician persuaded Calmette to allow his vaccine to be used to protect a child who had been born to a mother who had tuberculosis. This unplanned test of the vaccine was completely successful and Calmette, in collaboration with medical colleagues, then carried out extended trials. The vaccine was initially
used on newborn infants at the Charité Hospital in Paris.
In 1924 Calmette and Guérin published a historic paper in which they showed that vaccination trials on children undertaken in many parts of the world had clearly demonstrated the success and safety of the vaccine as a protective measure against tuberculosis. A new building was erected at the Pasteur Institute in 1928 specifically for the Service du BCG, signifying the importance of the cure. In the same year BCG was adopted by the Health Committee of the League of Nations. But in 1930, just at the time when BCG was gaining greater acceptance and thousands of children had been successfully treated, an unexpected tragedy occurred.
As with previous breakthroughs, there were critics who doubted the safety of the vaccine, fearing that the strain would not always remain avirulent. In what became known as the Lübeck disaster, 207 out of 259 children who had been vaccinated between the end of February and the beginning of April in 1930 contracted tuberculosis, and sadly, 72 of the infected children died.[26] This tragic event cast enormous doubt on the vaccine and created great personal anguish for its inventors. The whole world was profoundly shocked and Calmette was savagely attacked by many in the medical profession and in the press. Other doctors, however, particularly those in Germany who had successfully used the vaccine, rallied to his side.
The German health authorities held a rigorous and drawn out inquiry. Investigations revealed that the director of the public health laboratories at Lübeck had arranged for Calmette to send him a culture so that the BCG vaccine could be prepared in the city hospital laboratories but, because of careless practices during production, the vaccine they produced contained virulent bacilli. The German doctors who were found responsible were imprisoned and Calmette was absolved of any blame.
Production methods were overhauled and after another enquiry in 1932 the BCG was declared safe. Despite this clean bill of health, the vaccine was not widely used for some years which meant that tuberculosis remained a huge health problem globally in the first half of the twentieth century. After World War II there was an increased uptake, however, and from 1945 to 1950 relief organisations conducted an international tuberculosis campaign and vaccinated over 11 million children and adolescents in over twenty countries preventing a predicted increase in TB after the ravages of the war.[27] As a result of the introduction of BCG and the gradual introduction of a raft of health and hygiene measures in Europe, deaths from TB fell from 500 out of every 100,000 people in 1850 to 50 out of 100,000 by 1950.
Research into the vaccine continued and gradually its prophylactic value was accepted. Mass vaccination programs were eventually conducted in many countries including Japan, Russia, China, England, France and Canada. Although BCG was licensed in the United States in 1950, resistance to its use there has remained strong but in Great Britain the vaccine was widely accepted after a Medical Research Council investigation in 1959 guaranteed its safety. BCG is a safe vaccine because the virulence of the live bacilli it contains remains low and it is effective for both animals and humans because the tubercle bacilli of both bovine and human types are related closely enough to produce cross-immunity, as Robert Koch had suggested.
***
Camille Guérin outlived his colleague Albert Calmette by almost 30 years. Calmette died in 1933 a year after the tragedy at Lübeck. Although he was 70 years old, his death may have been hastened by the stress he suffered from the protracted enquiry and the responsibility he carried for the death of so many children when his hope had been to save them from a dreadful disease. Before his death in 1961, Camille Guérin, however, had the satisfaction of seeing the vaccine he had laboured over for two decades accepted as a safe prophylactic measure against tuberculosis. Today BCG is still a potent weapon against TB and is the most widely administered vaccine in the world. It reduces mortality from TB by about 90 per cent in vaccinated children.[28] How different things might have been if Albert Calmette had not survived World War I.
HOPES FOR A TB CURE GIVEN NEW LIFE
With the discovery during World War II of penicillin, the first antibiotic, the treatment of infections changed forever and hopes were raised that other drugs could be found to annihilate the micro-organisms that cause human disease. The quest to find a cure for TB was revived. Selman Waksman, a Russian-born American microbiologist, led the charge, initiating a calculated systematic search for antibiotics in the world of microbes. He spent his life studying the benign and dangerous micro-organisms that live in soil. Waksman coined the term antibiotic, which means ‘against life’, and was credited with giving the world streptomycin.[29] Although Waksman won the Nobel Prize for this achievement it was the work of his student Albert Schatz that made it possible. Acknowledgment of Schatz’s contribution came somewhat belatedly.
Selman Waksman was born in 1888 in a Jewish village near Kiev, Russia. It was a difficult time for Jewish people in Russia. They were a persecuted minority which made Selman’s goal to study at a university not easily attainable. Selman fought against the injustice of the pogroms initiated by the tsarist government. He organised a Jewish resistance group, a move that placed him in jeopardy. When Selman’s mother died in 1910 there was nothing to hold him in Russia, and hoping for a less repressed life he emigrated to the United States where he had relatives and began his life there working on their farm.
Determined to acquire a university education, Waksman took advantage of the opportunities available to him in his new country and won a state scholarship to study agriculture at Rutgers University in 1911. He gained a Bachelor of Science degree in 1915 and a Master’s degree the following year after which he undertook graduate studies at the University of California, being awarded a PhD in biochemistry in 1918.
In 1921 Waksman began work as a microbiologist for the New Jersey Agricultural Experiment Station and combined his academic pursuits with work in private industry. When he was just over 40 years old, in 1929, Waksman was appointed as a professor at Rutgers University. In the same way that Pasteur had gone against the accepted theories of his day, as with spontaneous generation, Waksman opposed the prevailing ‘protozoan theory of soil fertility’.[30] This was based on the assumption that protozoa consumed bacteria, sometimes to such an extent as to destroy soil fertility. Waksman’s evaluation of bacterial populations in the soil, their chemical properties and the complex balances between them seemed revolutionary at the time.
Before 1939, the year that World War II began, Waksman had not been interested in pharmacological research but his interest was piqued when one of his former students, René Dubois, discovered two soil-based antimicrobials (substances that kill microbes), tyrocidine and gramicidin. Although toxic to humans, these substances proved promising for treating some infections in animals. This discovery coincided with news that work was taking place in England on the development of penicillin, an antibacterial from a mould.
Waksman had long been interested in actinomycetes, a group of fungus-like bacteria, most species of which are harmless; so he made the decision to begin experimenting with soil-based fungi and bacteria.[31] He had already refined techniques that would enable him to isolate soil organisms, culture them and purify and crystallise soil-based substances. As was common practice, graduate students assisted Waksman with various aspects of his work, one of whom was Albert Schatz. It was Schatz who made a crucial discovery.
Born in 1920 in Connecticut, Albert Schatz was a graduate student at Rutgers University when he was drafted into the army in November 1942 during World War II. Working as a laboratory bacteriologist in an army hospital in Miami, Florida, he saw the miraculous success of the recently developed penicillin, which at that time was available in limited amounts to military personnel. Schatz’s stint in the army was short-lived and after being discharged in June 1943 because of a congenital abnormality in his lower spine he immediately resumed his doctoral research. In an oral history recorded at Rutgers, Schatz gave an account of how he became involved in a project to find a cure for tuberculosis. Doctors at the Mayo C
linic, the world-renowned hospital and medical practice based in Minnesota, had suggested to Selman Waksman that he try to find an antibiotic that would be effective against TB.
DrWaksman was disinclined to take on that project because he was afraid of tuberculosis. This disease had by then killed about a billion people in the last two centuries. That was more deaths than were caused by all other infectious diseases combined. However, I persuaded DrWaksman to let me do the TB project. He agreed, but, because I would be working with a virulent human strain of the tubercle bacillus, he transferred me from the laboratory adjacent to his office on the third floor of the Administration Building to the basement laboratory. He told me never to bring a culture of the tubercle bacillus to the third floor. And he never visited the basement laboratory.[32]After researching alone in the basement for three and a half months, Schatz found that the actinomycete Streptomyces griseus seemed effective against the ancient survivor, Mycobacterium tuberculosis. Albert Schatz had isolated the antibiotic that became known as streptomycin and he wrote the first paper about it in which he described the discovery. However, in January 1944 it was Selman Waksman, not Albert Schatz, who reported on the antibacterial properties of Streptomyces griseus and as a result tests on streptomycin were commenced in the Mayo Clinic. Favourable results with streptomycin on tuberculous guinea pigs led to human trials. By October, the first human patients were in treatment and streptomycin appeared to be having unprecedented success in curing their TB.
Smallpox, Syphilis and Salvation Page 11