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

Abstract

Postexposure prophylaxis (PEP) after intravaginal exposure to human immunodeficiency virus (HIV) was investigated using the HIV type 2 (HIV-2)/pig-tailed macaque transmission model. PEP for 28 days with the reverse transcriptase 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-associated provirus, antibody responses, and lymph node virus. Breakthrough infection 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 infection.

FIG. 1

HIV-2 load in plasma and CVL specimens through 24 weeks after intravaginal virus exposure in untreated control macaques (n = 4). Plasma vRNA levels are reported as log₁₀ copies per milliliter and virus levels in CVL supernatants are indicated as log₁₀ total copies per lavage specimen. The sensitivity limits are 100 copies/ml for plasma and 400 total copies for CVL supernatants with a 50-μl sample equivalent input into the assay system (dashed line).

FIG. 2

Longitudinal HIV-2 vRNA levels in plasma versus CVL supernatants after intravaginal virus exposure in experimental macaque groups (n = 4 each) receiving PEP with PMPA at the indicated times. Results are reported as in Fig. 1.