Most people infected with HIV are also infected with HSV-2, the major cause of genital herpes. Previous studies demonstrated that the risk of passing HIV to a sexual partner is greater when the HIV-infected person has genital ulcers caused by HSV, and that HIV levels are increased during genital HSV reactivation.
In the current study, researchers at the University of Washington and the research organization Impacta, in Lima, Peru, examined the effect of HSV-2 suppression on levels of HIV infectiousness.
Connie Celum, MD, MPH, Richard Zuckerman, MD, MPH and her colleagues in the research performed a randomised, placebo-controlled cross-over study of daily HSV suppressive treatment in a small group of HIV/HSV-2 co-infected men who have sex with men.
For the study, 20 men aged 22 to 41 were enrolled. The men studied had no prior antiretroviral therapy and were not currently receiving antiretroviral therapy for HIV infection.
They were randomly assigned to the anti-HSV drug, valacyclovir 500 mg, twice daily or matching placebo for initial treatment. After eight weeks, subjects had a "washout period" in which they received twice-daily placebo. Subjects then crossed over to the alternative treatment (placebo or valacyclovir) for eight weeks.
Participants visited the clinic three times a week during each treatment arm. At each visit, rectal secretions were collected and weekly blood samples were obtained to determine levels of HIV.
The research team discovered significantly reduced levels of HIV in blood by about 50 percent and rectal secretions by about 30 percent during the 8 weeks when the HIV/HSV-2 co-infected men received valacyclovir to suppress reactivation of HSV.
This reduction in HIV levels could have a significant impact on transmission of HIV. Since the only intervention was daily valacyclovir to suppress HSV, this study has added weight to the other evidence that HSV-2 reactivation increases HIV replication.
According to the researchers, additional "ongoing randomised trials will answer whether HSV suppression can reduce HIV transmission and address the potential for HSV suppression to delay anti-HIV therapy (antiretroviral) initiation."
This study is published in the November 15 issue of the Journal of Infectious Diseases, now available online.