By Martha Henry
It is always a shock to find out that what you had assumed was true simply is not. That is why clinical trials are so important to science. The unexpected results of a recent trial examining herpes and HIV demonstrates the importance of carrying out controlled trials to test preconceived beliefs.
Up to 90% of women with HIV infection in southern Africa also have genital herpes (HSV-2). Most people who are infected with HSV-2 do not know that they have the virus, which causes symptomatic genital sores and breaks in the skin but is frequently active without symptoms. Multiple studies had shown that infection with herpes was associated with an increased risk for HIV infection. However, whether treatment to suppress HSV-2 would decrease HIV transmission had not been tested.
The Partners in Prevention HSV/HIV Transmission Study, led by the University of Washington and funded by the Bill & Melinda Gates Foundation, looked at whether the use of acyclovir, a drug widely used for the safe and effective suppression of HSV-2, by persons who are infected with both HSV-2 and HIV could reduce the likelihood that they would transmit HIV to their HIV-uninfected partners.
The study was conducted among 3,408 African HIV-discordant couples, in which one partner had HIV and the other did not. In all the couples, the partner who had HIV also had HSV-2 infection. The study took place in seven countries in Africa (Botswana, Kenya, Rwanda, South Africa, Tanzania, Uganda and Zambia). In sub-Saharan Africa, the majority of new HIV infections occur among heterosexual HIV-discordant couples, many of whom are in stable partnerships and unaware that one partner has HIV and the other does not.
The study results, published in The New England Journal of Medicine in early February, were both surprising and disappointing. Researchers concluded that daily acyclovir therapy did not reduce the risk of HIV transmission when taken by people infected with both HIV and HSV-2. In other words, controlling the herpes of someone infected with HIV did not decrease the chance that he/she would infect a partner with HIV.
The Botswana portion of the study was conducted by the Botswana–Harvard AIDS Institute Partnership, under the direction of Dr. Max Essex. Though Essex was disappointed, he said the results are still useful. “It is important, first of all, because it shows that although the risk for infection by herpes and HIV go together, controlling the herpes infection with treatment does not reduce risk for infection with HIV. People should not treat herpes specifically to control HIV spread, but should treat to control the pain and symptoms of herpes.”
Essex said the study was also important for showing how viral genetic sequencing can be used to determine if a study participant became infected from his/her partner or from someone outside of the study. “The study showed how effectively researchers can use viral sequencing genetic linkage to verify the source of the infection. We found that two-thirds of the newly infected people who didn’t get acyclovir did get infected from their partner.”