In this study of an issue that has implications for public health and for clinical care of patients with HIV, a team from UNC examined the effect of antiviral therapy on HIV in blood and in semen, and discussed whether transmission of resistant virus could occur even when a patient is using effective anti-HIV medications.

The study enrolled 15 men with CD4 cell counts below 200, at least 6 months of ZDV (AZT) use, and no prior indinavir or 3TC use, and randomized then to a double-blinded regimen of either AZT/3TC/placebo or AZT/3TC/indinavir. Ten were randomized to the three drug arm and 5 to the two drug arm. Both arms had similar baseline semen and blood HIV levels, around 3.5 logs and 4.8 logs respectively. Semen plasma HIV levels could be measured down to the 1000 copies/mL level, while blood plasma was measured to the 400 copies/mL level.

After 24 weeks of treatment, semen HIV levels were below detection in 90% of the men in the triple combination arm, and in 80% of the two-drug arm, while blood HIV levels were undetectable in 80% and 60% respectively.

The researchers concluded that while effective antiretroviral therapy can reduce the levels of HIV in semen, the chance for HIV transmission still exists, given the lack of uniform response to therapy and the limits of sensitivity of the semen HIV viral load test. Additionally, since semen can be found when a patient is on antiviral treatment, the chance for transmission of resistant HIV also exists. This study provides further evidence that transmission prevention efforts are doubly important in the age of HAART.