Chimpanzee Studies
Before being tested in humans, two separate tests conducted by Genentech, Inc. demonstrated that vaccines containing gp120 were able to protect chimpanzees from live HIV infection. Since chimpanzees are the only laboratory animal susceptible to infection by the virus, the ability to protect them with a gp120 vaccine was an encouraging step forward.
In the first test, the chimpanzees were vaccinated with a gp120 formulation designed to protect against one particular strain of HIV. The vaccinated chimps, along with those that received placebo, were then injected with high doses of live HIV from the same strain used to make the vaccine. All of the vaccinated chimps were protected.
In the second test, the vaccinated chimps were challenged with an HIV strain that was significantly different from the one used to make the gp120 vaccine. The results were the same: The vaccinated chimps were protected and the unvaccinated animals became infected.
Both studies were carried out by Phillip Berman, Ph.D., who at the time was a scientist at Genentech. He is now VaxGen’s Senior Vice President of Research and Development. The importance of Dr. Berman’s discoveries were summarized by Dr. Jorg Eichberg. At the 1990 International AIDS Vaccine Conference, Dr. Eichberg had compared 17 separate HIV vaccine studies using chimpanzees. He concluded that only gp120 from Genentech was able to protect chimps from live HIV challenges.