Acyclovir reduces occurrence of HSV-2 genital ulcers but does not affect HIV transmission

Research from a five-year international clinical study shows that acyclovir, a commonly prescribed drug used to suppress symptoms of the herpes virus, does not affect HIV transmission by people with both viruses.

The study, conducted by the Partners in Prevention HSV/HIV Transmission Study, was released by the New England Journal of Medicine in its online edition Jan. 20 and will follow in the print edition Feb. 4.

The largest risk group worldwide, but particularly in Africa and Asia, for contracting HIV is stable, heterosexual couples where only one partner is infected. Among those infected, about 90 percent also have a herpes simplex virus-2 (HSV-2), the most common cause of genital herpes, said study co-author Kenneth H. Fife, M.D., Ph.D., professor of medicine in the Division of Infectious Diseases at the Indiana University School of Medicine.

"Logic indicated that outbreaks of HSV-2 sores could enhance the transmission of HIV," said Dr. Fife. "This is the first comprehensive study to look at the potential for reducing the transmission of HIV through treatment of the herpes virus."

Multiple studies have shown that frequent genital herpes recurrences increase the amount of HIV in the blood and genital tract. It is known that HIV virus is shed through genital herpes ulcers and people with those ulcers transmit HIV to other more efficiently.

Five preliminary studies showed that it is possible to decrease the amount of HIV in the blood and genital tract through treatment to suppress HSV-2. However, those studies did not measure whether there also was a reduction in HIV transmission.

The study found that acyclovir reduced the occurrence of HSV-2 genital ulcers by 73 percent and thus the amount of HIV present in the blood and genital tract decreased twofold.

In spite of the reduction of HIV present in blood levels, the researchers found there was no significant difference in the transmission of HIV. Laboratory testing showed there were 41 infections in the group taking acyclovir and 43 in the placebo group.

This Partners in Prevention study was conducted at 14 sites in seven sub-Saharan counties: Botswana, Kenya, Rwanda, South Africa, Tanzania, Uganda and Zambia. Recruitment began in November 2004 and concluded in October 2008. Initial results were presented at the International AIDS Society meeting in Cape Town, South Africa, on July 22, 2009.