July 11, 2002
It is well documented that discontinuation of antiretroviral therapy leads to a prompt rebound in plasma HIV RNA, or viral load. Most patients will return to their pre-treatment baseline within four to six weeks off therapy. Less well defined are the dynamics of viral rebound in semen, a crucial determinant of sexual HIV transmission.
Twelve HIV-infected patients on combination antiretroviral therapy participated in this study comparing plasma and seminal HIV RNA. At baseline, 8/12 had undetectable levels (less than 50 copies) in the blood, and all but one had undetectable seminal levels. Treatment discontinuation was done in 7/12 patients because of lipodystrophy; the rest of the discontinuations were voluntary. At baseline and every four weeks, blood and semen samples were obtained for viral load measurements.
After stopping therapy, all patients experienced virologic rebounds in both plasma and semen, with levels ranging from 15,266 to more than 500,000 and 1,096 to more than 1 million in plasma and semen respectively. While there was a correlation between levels in the plasma and semen, this correlation was not perfect. In those patients who resumed therapy, declines in HIV RNA occurred in both compartments, although not always to undetectable levels. No resistance testing of either plasma or seminal isolates was presented.
Since the best described correlate of the risk of HIV transmission to a sexual partner is the plasma viral load, and since, in general, changes in plasma move in parallel with changes in semen, it is reasonable to assume that treatment interruptions may increase the risk of transmission. As the presenting author emphasized at the conclusion of her talk, it is imperative that both clinicians and people with HIV realize this potential disadvantage to treatment cessation, and that efforts for risk reduction are reinforced.
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