March 16, 2012
A new study by Emory University researchers is seen as a step toward the development of a vaccine to prevent HIV infection. In the team's experiment, an injection protected monkeys against repeated exposure to the nonhuman version of HIV. The results were presented in Seattle at the 19th Conference on Retroviruses and Opportunistic Infections.
The injection uses HIV proteins to prime the body against a viral attack, as well as a protein, GM-CSF, that triggers the immune response, causing the body to release antibodies blocking HIV from entering the cells.
The monkeys received two injections, followed by two booster shots each two months apart. Beginning six months later for a 12-week period, the animals were repeatedly exposed to simian immunodeficiency virus (SIV). "Repeated challenges in animals are used to mimic sexual transmission," said co-author Dr. Harriet Robinson, of GeoVax Labs.
The injection was found to be 87 percent effective per exposure; overall protection was 70 percent. "The hope is that the results in nonhuman primate models will translate into vaccine-induced prevention in humans," Robinson said.
This good news follows a recent study by a Harvard University team, which reported that a mixture of vaccines reduced monkeys' risk of SIV infection by more than 80 percent. Further, in those that did become infected, the vaccine combination "substantially" reduced SIV levels in the blood.