Virology in order to immunize others. In 1717 Lady Mary Wortley Montagu observed the practice in Istanbul and attempted to popularize it in Britain, but encountered considerable resistance. In 1796 Edward Jenner developed a much safer method, using cowpox to successfully immunize a young boy against smallpox, and this practice was widely adopted. Vaccinations against other viral diseases followed, including the successful rabies vaccination by Louis Pasteur in 1886. The nature of viruses however was not clear to these researchers. In 1892, the Russian biologist Dmitry Ivanovsky used a Chamberland filter to try to isolate the bacteria that caused tobacco mosaic
History of smallpox cowpox were arising. Jenner was missing crucial information which he later discovered in 1796. Jenner hypothesized that in order to become immune to smallpox using cowpox, the matter from the cowpox pustules must be administered at maximum potency; else it was too weak to be effective in creating immunity to smallpox. He deduced that cowpox was most likely to transfer immunity from smallpox if administered at the eighth day of the disease. On May 14, 1796, he performed an experiment in which he took pus from a sore of a cowpox infected milkmaid named Sarah Nelmes and applied it to