Experimental AIDS Vaccine Keeps Virus Under Control in Monkeys
The vaccinated monkeys and the unvaccinated monkeys all became infected with the virus, but the vaccinated animals remained healthy. Their immune systems continued to produce a large number of disease-fighting T-cells, and the number of copies of the virus in their blood quickly began to dwindle -- both signs that their bodies were successfully fighting off the infection.
The unvaccinated monkeys, however, had severe depletion of their T-cells and had evidence in their blood that the virus was reproducing itself with abandon. The unvaccinated monkeys developed multiple life-threatening infections in a disease course mimicking that of advanced AIDS in humans.
"This is as exciting an animal protection result as we've seen, due to the fact that they're protecting against [T-cell] loss, and virus loads are going down to undetectable," says James Bradac, PhD, chief of the preclinical research and development branch, division of AIDS vaccine and research prevention program, at the National Institute of Allergy and Infectious Diseases in Bethesda, Md.
Bradac, who was not involved in the study, tells WebMD that "for the human experience, we've got to see what happens when you hold these animals [for more time], and a key is to see whether this type of situation will prevent transmission to others. You don't want to merely keep someone alive a few years longer; we've got to have higher goals to prevent the spread of the epidemic."
Peggy Johnston, PhD, assistant director for AIDS/HIV vaccines at the National Institute of Allergy and Infectious Diseases, tells WebMD that the vaccine "may even be better in humans, because these animals are exposed to a very high amount of virus to ensure that all the [unvaccinated monkeys] get infected, and that is probably much larger than an average human exposure [to HIV], so it could even be better -- we don't know."
Robinson and researchers from the National Institute of Allergy and Infectious Diseases are currently collaborating. They are working on developing and testing the vaccine in early human trials, pending approval from the institute, which funded the current study.