Efficacy of live-attenuated and whole-inactivated simian immunodeficiency virus vaccines against vaginal challenge with virulent SIV.

The ability of two vaccine preparations (UV-psoralen inactivated SIV administered intramuscularly and live-attenuated SIV inoculated intravaginally) to prevent genital transmission of virulent SIV in rhesus macaques was tested. Two of six whole-inactivated SIV vaccinated macaques, three of five live-attenuated SIV vaccinated macaques, and four of six controls became persistently infected after two separate intravaginal inoculations with a 50% animal infectious dose of virulent SIV. No association was observed between levels of SIV-specific antibodies in serum or vaginal secretions prior to challenge and subsequent infection with virulent SIV.