Max Theiler health at the Yale School of Medicine and the School of Public Health from 1964 to 1967. After passing the yellow fever virus through laboratory mice, Theiler found that the weakened virus conferred immunity on rhesus macaques. The stage was set for Theiler to develop a vaccine against the disease. Theiler first devised a test for the efficacy of experimental vaccines. In his test, sera from vaccinated human subjects were injected into mice to see if they protected the mice against yellow fever virus. This "mouse protection test" was used with variations as a measure of immunity until after World
Max Theiler War II. Subculturing the particularly virulent Asibi strain from West Africa in chicken embryos, a technique pioneered by Ernest Goodpasture, the Rockefeller team sought to obtain an attenuated strain of the virus that would not kill mice when injected into their brains. It took until 1937, and more than 100 subcultures in chicken embryos, for Theiler and his colleague Hugh Smith to obtain an attenuated strain, which they named "17D". Animal tests showed the attenuated 17D mutant was safe and immunizing. Theiler's team rapidly completed the development of a 17D vaccine, and the Rockefeller Foundation began human trials in South