Regular use of a new vaginal gel containing the antiretroviral (ARV) drug tenofovir has been found to reduce the risk of acquiring herpes simplex virus type 2 (HSV-2) by almost 50 percent, according to a new trial conducted by VOICE (The Vaginal and Oral Interventions to Control the Epidemic).

The research conducted by the National Institutes of Health-funded Microbicide Trials Network (MTN) has added to the growing body of evidence that tenofovir can be used to manage one of the most prevalent sexually transmitted diseases affecting sexually active women in sub-Saharan Africa — HSV-2.

HSV-2 is a contagious disease that often causes genital herpes. The viruses are known to cause lifelong infections as they cannot be eradicated from the body. The route of infection is generally from a man to a woman, rather than the other way round. Scientists have been trying to find a cure for genital herpes because of its role in boosting the risk of HIV infection. No biomedical cures are currently available to cure this disease.

The purpose of VOICE trial is to examine the efficacy of ARV approaches in preventing HIV in women. More than 5,029 women from around Africa were involved in the study. While initial results showed that none of the products, including tenofovir gel, was unsuccessful in preventing HIV, the research was amended to check the role of the drugs in preventing HSV.

A previous study, called CAPRISA 004, of 889 women in South Africa found that using the gel reduced the risk of HSV-2 by 51 percent compared to a placebo. This was regarded as a milestone, since this was the first time that any kind of biomedical prevention method was shown to be effective against HSV-2.

So, VOICE decided to check the effect of the gel on women who they knew had used their product with tests that detect the presence of the drug in stored blood samples.

"In this closer examination, we saw tenofovir gel was associated with a significant reduction in HSV-2 risk. The difference was actually quite profound between the two groups of women – those who used the gel and those who hadn't," commented lead researcher Dr. Jeanne Marrazzo in a statement.

Women who frequently used the gel were 46 percent less likely to acquire HSV-2 as compared to women who used it infrequently or did not use it at all. Out of the 566 HSV-2 negative women who had enrolled, 527 continued to remain HSV-2 negative after one year of regular usage, as indicated by the presence of the drug in their blood, while 77 who did not have any trace of the drug in their blood sample tested HSV-2 positive. 

While the results are very encouraging, further tests are needed to determine the drug’s potential, Marrazzo said.

Source: Marrazzo J, et al. HIV Research for Prevention (HIV R4P) Meeting. 2014.