Background: Transmitted drug-resistant HIV slowly reverts in the blood to drug-sensitive virus. The environment of the male genital tract (MGT) may result in even slower rates of reversion to drug susceptibility.
Methods: We measured the decay of resistance in longitudinally collected blood and semen samples from 5 individuals newly infected with HIV containing resistance mutations to nonnucleoside reverse-transcriptase inhibitors (NNRTIs). We also investigated the sexual transmission of HIV to and from these participants.
Results: In 3 of the 5 individuals, NNRTI resistance persisted in blood and semen throughout follow-up (mean, 296 days after the estimated day of infection [EDI]). In the other 2 individuals, NNRTI resistance persisted in blood and semen for 871 and 1179 days after the EDI; however, even after NNRTI resistance had fully reverted in blood, it remained readily detectable in semen. Two transmission groups were identified among these participants--one as the recipient partner and the other as the source partner.
Conclusions: Transmitted drug-resistant HIV, which persists in blood for years, may revert to wild type even more slowly in the MGT. This prolonged persistence in the MGT may contribute to the high prevalence rates of transmitted drug resistance.