Pasteur and the Development of the Vaccine
Immunology may seem to be an elaborate class of study today; yet there was a time when how the body defended itself against foreign pathogens was quite a mystery. However, one scientist during the 1800’s with others such as Spallazani and Koch helped develop the study of immunology by debunking the “Theory of Spontaneous Generation,” thus revolutionizing the path that biology and biochemistry would eventually take. This discovery coupled with such techniques as pasteurization, study of infectious diseases, and the development of vaccines helped produce the field that is now called immunology, and the man that these works can be attributed to is none other than Louis Pasteur.
Louis Pasteur was born in December 27, 1822 in Jura, France. Pasteur was an incredibly intelligent man and by the age of twenty he had already obtained the position of assistant teacher at the College of Besancon. When only twenty-six his independent studies led to his discoveries of chemical molecules that were identical yet mirror images. This work became the basis of a new science, stereochemistry. However Pasteur’s contributions to science had just begun. He became an expert on fermentation, studying why alcohol became contaminated with undesirable substances during fermentation. With these studies subsequently led to his discovery of microorganisms which were responsible for fermentation. The experiments he conducted with specially designed flasks led him to develop the “Germ Theory of Disease” which as stated previously contributed to rectify the previously accepted “Theory of Spontaneous Generation.”
These astounding precursors all led one of his most important discoveries, the development of the vaccine. Others such as Jenner had previously developed “vaccines” yet they did not understand the infectious agents that caused disease. On the other hand, Pasteur was hard set of finding these microbes that were responsible for disease. Pasteur acquired the precursors to developing vaccines from the study Louvrier’s cure for anthrax which consisted of a strange ritual of rubbing the cow vigorously until hot, cutting a large gash which would then be flooded with turpentine, and subsequently covering the cow with unmentionables. Pasteur performed an experiment where he injected some of Louvrier’s cow stock with anthrax and told Louvrier to perform his cure on a section of the cattle. The ones that were treated with Louvrier’s cure survived while the others did not. Pasteur then decided to inject the cattle that had survived with the cure with another dose of anthrax that he said could “kill a rhinoceros.” The result was astounding, the cows which had initially fought of the anthrax with the help of Louvrier’s cure were now immune to even the most lethal strain of anthrax and survived the second dosage. From the results of his experiments performed with Louvrier, Pasteur deduced that if he could give an animal a little dose of anthrax or another pathogen and it would survive, then it would forever be immune to further infections.
Pasteur with the help of his two assistants who were young physicians Roux, and Chamberlin begin to develop a way to create a non-lethal dose and therefore create a vaccine. They begin by researching with a disease that afflicted chickens named chicken cholera. They developed several cultures of the bacteria and cultures began to clutter the Pasteur’s laboratory. He was about to dispose of the cultures when instead he asked Roux to inject some of the bacteria from the abandoned cultures from several weeks past into some of the chicken test subjects. The chickens infected with the old strains of the bacteria got sick and showed the characteristic symptoms of the disease yet recovered and once were again healthy. Once injected with more lethal strains of the bacteria, the results were similar to those witnessed in the experiments on Louvrier’s cattle. The chickens which had survived the initial infection were immune to the new more deadly strains. We now know that the abandoned cultures Pasteur had developed most probably contained weakened forms of the pathogen as it mutated in order to survive since the conditions it was in were so poor. However, Pasteur did not have the hind sight we have now but still used this basic idea as the principle for developing vaccines for several other microbes.
Yet, rabies proved to be a difficult disease for Pasteur to study because he was never able to isolate the microbe responsible for spreading the disease. After testing several tissues of several dogs, Pasteur proposed to Roux that perhaps the disease resided in the spinal column and brain. Roux performed a trephine on a dog’s skull and injected the rabies pathogen. Surely enough, the dog contracted the rabies disease and eventually died for the benefit of science. Further experiments were however not as productive. Every dog that Pasteur and his assistants injected with the rabies virus would eventually die. However, there was a chance mishap and one of the dogs got sick with rabies but recovered. A trephine procedure was performed on the dog and the rabies pathogen was once again injected. This dog survived and proved to Pasteur and his team that there was hope for developing a less virulent strain of the rabies pathogen. Pasteur asked his assistants Roux and Chamberland to perform an odd experiment where they would remove the spinal chord from rabbits which had died of rabies and dry them in germ free bottle for fourteen days. They then created several strains at each day increment and injected them into the head of dogs once again but starting from the oldest first and progressively increasing to the most virulent strain. To their utmost elation the dogs treated with the stepwise injections of weakened viruses did not succumb to the usual symptoms of rabies, yet were immune to the usual lethal strain. Pasteur had now set out what he had long ago set out to accomplish. Pasteur was hesitant to use the vaccine in humans however on June 6th 1885 they made their first injection into a small boy who had been severely mauled by a rabid dog, who would have surely died without aid. The vaccination process was a success and the boy survived through all fourteen injections and was seemingly cured of any traces of rabies disease. This was the final step in the development of Pasteur’s vaccines and verified that they had truly created something magnificent.
Pasteur accomplished a great deal in his lifetime and his interest in immunology was not hindered by his lack of a medical degree. His initiative and creativity allowed him to discover some of the most quintessential points of modern sciences. Immunology has progressed a great deal since Pasteur’s time but the ingenuity he had will surely be necessary to progress yet further. As Pasteur once said “Chance favors the prepared mind.”
