Efficacy of postexposure prophylaxis after intravaginal exposure of pig-tailed macaques to a human-derived retrovirus (human immunodeficiency virus type 2)

Postexposure prophylaxis (PEP) after intravaginal exposure to human immunod eficiency virus (HIV) was investigated using the HN type 2 (HIV-2)/pig-tail ed macaque transmission model. PEP for 28 days with the reverse transcripta se inhibitor (R)-9-(2-phosphonylmethoxypropyl)adenine (PMPA; tenofovir) was initiated 12 to 72 h following HIV-2 exposure. Systemic infection was not evident in the 12- and 36-h groups, as defined by plasma viremia, cell-asso ciated provirus, antibody responses, and lymph node virus. Breakthrough inf ection in the 72-h group was detected at week 16 post-virus exposure. These results demonstrate for the first time using a vaginal transmission model that early intervention after high-risk sexual exposures may prevent infect ion.