Three gene variants in the DNA of 486 AIDS patients appear to play a role in containing and slowing the HIV virus, according to research published Thursday.
The researchers hope their finding will lead to a vaccine that would boost the protective effects of one or more of these genes, and help the body's own immune system overcome an infection.
One gene variant looks specially promising, the scientists said in a study to appear in the Friday edition of the journal Science.
"These results not only approximately double our understanding of the factors that influence variation amongst individuals in how they control HIV-1, but also point toward new mechanisms of control," said David Goldstein, of Duke's Institute for Genome Sciences and Policy at North Carolina's Duke University and chief author of the study.
The international team of geneticists worked for 18 months in carefully selecting patients and using the latest in genome-wide screening technology to discover the three genes.
The research found that some patients with specific gene variants in key immune system cells appear to be much better controlling the proliferation of the AIDS virus after infection.
"As we expand the number of patients in future studies conducted by CHAVI (Center for HIV/AIDS Vaccine Immunology) researchers, we aim to discover even more polymorphisms that could provide additional clues how some patients are better able to control the virus than others," Goldstein said.
"This should ultimately lead to novel targets for vaccines, the primary goal of CHAVI," a seven-year project launched in 2005 by the National Institute of Allergy and Infectious Diseases (NIH).
Two of the newly discovered gene variants were found in genes controlling the human leukocyte antigen (HLA) system, which plays a "major role" in the immune system by identifying foreign invaders and "tagging" them for destruction.
Two of the HLA genes, known as HLA-A and B, are turned off by the HIV virus when it enters the body, which keeps the immune system from recognizing the virus as foreign.
However, the HLA-C gene is apparently not turned off by the AIDS virus, suggesting that for some individuals at least HLA-C is involved in controlling the HIV virus, the researchers said.
The HLA-C gene may represent an Achilles heel of HIV, according to Goldstein.
A vaccine could be designed to elicit an HLA-C mediated response that the HIV virus might be unable to defuse, the expert added.