LOS ANGELES — Treating genital herpes simplex virus with acyclovir diminishes vaginal HIV shedding and plasma HIV levels in women coinfected with HSV and HIV, which suggests that treating herpes could have a role in reducing HIV transmission, according to two studies presented at the 14th Conference on Retroviruses and Opportunistic Infections.
A study conducted in Thailand by the U.S. Centers for Disease Control and Prevention found that 55% of treated women had a significant reduction in vaginal viral shedding during their treatment, said Dr. Eileen Dunne, of the Division of Sexually Transmitted Diseases Prevention of the CDC.
In a study from South Africa, treated women had a reduction in herpes simplex virus type 2; 63% less vaginal shedding, compared with placebo-control women; and a 43% reduction in plasma HIV levels, said Dr. Sinead Delany-Moretlwe, director of research for the reproductive health and HIV research unit at the University of the Witwatersrand, Johannesberg, South Africa.
Neither study was without some equivocal results that tempered the investigators' overall assessment of the findings, but both investigators nevertheless concluded that their trial showed benefit. Both also noted that although their studies were short, they were optimistic that longer trials, currently underway, of HSV suppressive therapy and actual HIV transmission would find that such therapy reduced transmission.
Each trial lasted only 3 months.
The Thailand study analyzed data from 67 women coinfected with HSV and HIV. The women were assigned into one of two groups. One group was treated for 1 month with acyclovir 800 mg twice daily, and the other served as a control. After a 1-month washout with no drugs, the groups were switched.
Overall, 34% of the women had no vaginal HIV shedding at baseline and so had no change through the trial. However, 55% of the subjects did have a significant reduction in HIV shedding while on acyclovir. And there was a 2.8-fold drop in HIV load in vaginal lavage samples, which was statistically significant, though the mean 0.4-log drop in viral load is not far above the 0.3 sensitivity limit of HIV viral load testing.
Dr. Dunne noted, however, that most of the women had never had herpes symptoms, and their HIV was in such an early stage that it was not being treated. And, she said, the treatment might have a more profound effect on people with more advanced disease.
“You might expect the impact would be greater in a group with immunosuppression or a group with symptomatic herpes,” she said.
“We are hopeful that this study foreshadows positive results from the ongoing trials that are evaluating the effect of suppressive therapy [of HSV] on transmission of HIV,” she added.
The South African study had 169 women treated with acyclovir (400 mg twice daily) or placebo for 3 months. Like the patients in the other study, they were HIV positive and not on antiretroviral therapy.
The study found no statistically significant drop in the vaginal HIV viral load. But it did find a 2.4-fold decline in mean plasma viral load relative to placebo, and a larger percentage of the treated patients were found not to be shedding HIV at all visits. Of the treated women, 23% were found to be shedding at fewer than half of their weekly visits, versus 17% of the placebo-control women.
By the third month, HSV shedding had been reduced by 63% in the treated patients, compared with the placebo group.
“We believe this warrants further investigation over a longer follow-up,” Dr. Delany-Moretlwe said.