Louis Pasteur

Louis Pasteur, probably the most important figure in the history of immunology, was a chemist by training. As a result of his studies on fermentation, Pasteur firmly established that bacteria were the source of fermentative activity and it was he who finally disproved the ideas of spontaneous generation of life forms. His studies on bacteria and bacterial disease led to methods of diagnosing these diseases by isolating their bacterial causes. Pasteur was a very practical man and his interest in preventing disease led to the discovery and systematic development of vaccines against fowl cholera, anthrax and rabies. These key discoveries led to the establishment of immunology as a discipline

Tizard Immunology 4th ed. p377

1885 Pasteur oversaw the injections of the child Joseph Meister with "aged" spinal cord infected with rabies virus. Pasteur used the term "virus" meaning poison but he had no idea of the nature of the causative organism. Although the treatment was successful, the experiment itself was an ethical violation of research standards. Pasteur knew he was giving the child successively more dangerous portions