NEUTRALIZING ANTIBODIES ADMINISTERED BEFORE, BUT NOT AFTER, VIRULENT SHIV PREVENT INFECTION IN MACAQUES

By subcutaneous inoculation of SHIVKU-2 in the hands of macaques, we d eveloped a model of human immunodeficiency virus type-1 (HIV-1) occupa tional infection due to needle-stick injury and used the model to dete rmine whether neutralizing serum to SHIV administered before or after virus inoculation could either prevent or abort infection, respectivel y. Six rhesus macaques were given 15 ml/kg pooled anti-SHIV plasma and challenged 24 hr later with approximately 300 animal infectious doses of SKIVKU-2, subcutaneously. Three of the six macaques completely res isted infection with SHIVKU-2 A fourth animal failed to yield infectio us virus, but DNA extracted from its peripheral blood mononuclear cell s (PBMC) and lymph nodes had viral sequences. Partial resistance was n oted in the other two animals because virus recovery was delayed compa red with the control animals. In contrast, six of six macaques given t he same dose of anti-SHIV plasma 18 hr after exposure to virus became infected, as did two of two macaques given anti-SHIV plasma only 2 hr after exposure to virus. Our results suggest that neutralizing antibod ies may have a prophylactic but not a therapeutic role in HIV-1 infect ions.