Viral load rebounds rapidly in semen to potentially infectious levels following interruption of combination antiretroviral therapy (cART), according to French research published in AIDS.
Increases in viral load in both blood and semen were observed within two weeks of treatment interruption. Four weeks after stopping therapy, all participants had detectable virus in their semen. Viral load in semen peaked at approximately 16,000 copies/ml, high enough for transmission to sexual partners.
“Early HIV-RNA rebound was observed in all participants in both compartments,” comment the authors. “This finding supports evidence of a very high risk of sexual transmission during self-driven cART breaks or during ATI [antiretroviral treatment interruption] stemming from clinical trials. Thus, prevention strategies for HIV-negative partners of HIV-infected participants undergoing ATI need reinforcement (counselling, condoms, PrEP).”
There is now overwhelming evidence that people with an undetectable viral load when taking cART cannot transmit HIV to their sexual partners. Undetectable = Untransmittable has been widely endorsed and is now an important component of HIV prevention strategies.
Continuous HIV therapy with high levels of adherence is needed to maintain sustained viral suppression. However, it is unclear how quickly and to what level viral load in the genital tract rebounds when cART is interrupted. This is an important question for people using HIV treatment as prevention. It also has implications for therapeutic and vaccine trials which typically involve interruption of cART.
The ten HIV-positive men were taking part in a randomised, placebo-controlled vaccine study (VR102/ANRS149-LIGHT). They were randomised to receive an active vaccine or placebo between baseline and week 24 of the study, then interrupted antiretroviral treatment at week 36. Participants were able to resume cART at week 48 (or before) if viral load rebound occurred. The original study’s primary outcome was viral load in blood plasma at week 48, following the 12-week interruption.