UW Today

This is an archived article.

February 28, 2008

Bacteria in women may slow HIV transmission

Beneficial bacteria found in healthy women help to reduce the amount of vaginal HIV among HIV-infected women and make it more difficult for the virus to spread, boosting the possibility that good bacteria might someday be tapped in the fight against HIV.

The findings come from physicians and scientists at the UW and the University of Rochester Medical Center, who worked together in an effort to learn more about how HIV survives and spreads from person to person. The study included 57 women in Seattle and Rochester, and was conducted through the Women’s HIV Interdisciplinary Network, which is based at the UW.

The team studied the vaginal environment, examining the mix of bacteria that reside there and taking into account several other factors. Physicians tracked the level of HIV virus in the vagina as well as infection by common sexually transmitted diseases like trichomoniasis, gonorrhea, chlamydia and other more common types of vaginal infections.

Physicians also monitored the levels of beneficial bacteria known as Lactobacillus in the vagina, as well as hydrogen peroxide, which is produced by the bacteria and hinders the virus. They also measured the level of HIV in the women’s blood and the rate of progression of the disease overall.

The team found that women with hydrogen peroxide-producing Lactobacillus in the vagina had lower levels of HIV virus in genital secretions — what physicians call the genital viral load. Physicians know that the lower the level of HIV in the sexual tract, the less likely that the virus will be spread from person to person through sexual contact.

Scientists have previously recognized from laboratory studies that Lactobacillus might give women some natural protection against HIV. The bacteria, commonly found in most women, bind to the virus and secrete hydrogen peroxide. The bacteria are a close cousin of the Lactobacillus bacteria found in the small intestine, a type of good bacteria widely found in yogurt.

The research was presented this month at the Conference on Retroviruses and Opportunistic Infections in Boston by Jane Hitti, UW associate professor of obstetrics and gynecology. Robert Coombs, UW professor of laboratory medicine and of medicine, is the principal investigator for the study.