Study finds HIV-infected men at risk for spreading HIV despite taking HAART

Researchers from Boston University School of Medicine (BUSM) and Fenway Health have found that highly active antiretroviral therapy (HAART) does not completely suppress HIV in the semen of sexually active HIV-infected men who have sex with men (MSM). The findings, which currently appear on-line in AIDS, could indicate a potential transmission risk in MSM, who are highly susceptible to HIV infection.

Approximately 33.3 million people worldwide are living with HIV/AIDS, and 1.8 million deaths and 2.6 million new infections occur annually. Unprotected intercourse is the most common route through which HIV-1 is transmitted, and semen of HIV-infected men is an important source of HIV. Whereas the HIV/AIDS epidemic in Sub-Saharan Africa is generalized with approximately equal percentages of infections occurring in men and women, the epidemic in the United States and many other developed countries is concentrated in men who have sex with men. HAART, which is the primary treatment for HIV/AIDS, consists of a combination of potent anti-HIV drugs, which generally suppresses HIV levels in blood and semen, and HIV transmission to sex partners. However, sexually active MSM have a high prevalence of sexually transmitted infections which are a risk factor for HIV transmission.

To determine what percentage of sexually active HIV-infected MSM on HAART have HIV in their semen, the research team, headed by Deborah Anderson, MD, professor of obstetrics and gynecology at BUSM, recruited 101 men from Fenway health, Boston. They measured levels of HIV in blood and semen, and examined the relationship between HIV in semen and other clinical, behavioral and biological variables.

Eighteen percent of the men had HIV in blood despite being on HAART, and half of these men also had HIV in semen. "It has been shown before that HIV levels in peripheral blood are an important predictor of seminal HIV," explained lead author Joseph Politch, PhD, research associate professor in obstetrics and gynecology at BUSM.

HAART Highly Active Anti-Retroviral Therapy (HAART) consists of 3 or more highly potent anti-HIV drugs, commonly reverse transcriptase inhibitors and protease inhibitors.

The principle that lies behind HAART is that a single drug therapy may be successful for a while, but because HIV changes to avoid detection, drug-resistant strains will often arise in the patient. (This happens through a kind of evolution by natural selection - any new viruses which happen to be resistant to the drug will go on to multiply, while the others are stopped.) The chances of a HIV genome mutating such that it can resist three separate drug treatments at once, however, is so small that the pressure of this therapy prevents the emergence of resistant strains.

Of the 83 men with undetectable HIV in blood plasma, 25 percent had HIV in their semen. Detection of HIV in semen was strongly associated with high-risk (unprotected) sex behavior, sexually transmitted infections and genital inflammation.