People who don’t become infected with HIV despite engaging in unsafe sex or other high-risk behaviors may want to thank their lucky genes.

A new study suggests that certain genetic variants may help confer protection against infection with the virus that causes AIDS.

The study, presented here at the XVI International AIDS Conference, involved more than 850 sex-trade workers in Kenya.

Most of the women were HIV-positive, but 130 remained HIV-negative despite having sex with more than 500 infected men over a three-year period.

Seeking to find out if any genetic links could explain their resistance to the virus, Canadian researchers homed in on a gene called human leukocyte antigen-G, or HLA-G, that helps the immune system recognize foreign invaders such as HIV.

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The study showed that sex workers who didn’t harbor the virus were about twice as likely to have certain HLA-G variants, compared with sex workers who were infected.

The research team included Francis Plummer, MD, of the University of Manitoba in Winnipeg, Canada.

The next step is to figure out why these variants are associated with resistance, says researcher Will Turk, an undergraduate at the University of Winnipeg in Manitoba.

“If we can figure out why, we might be able to design a drug to lower infection,” Turk tells WebMD.

Joep Lange, MD, PhD, a leading AIDS specialist from the University of Amsterdam, agrees.

Understanding which genetic variants keep the virus from taking hold in the body may also help in the development of vaccines to prevent HIV, he says.

The study was one of several dozen highlighted as being noteworthy by the conference organizers. About 4,500 studies are being presented at the meeting.

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SOURCES: XVI International AIDS Conference, Toronto, Aug. 13-18, 2006. Joep Lange, MD, PhD, professor of medicine, University of Amsterdam. Will Turk, University of Winnipeg, Manitoba, Canada.

By Charlene Laino, reviewed by Louise Chang, MD