Highly Attenuated Vaccine Strains of Simian Immunodeficiency Virus Protect against Vaginal Challenge: Inverse Relationship of Degree of Protection with Level of Attenuation

Abstract

Three different deletion mutants of simian immunodeficiency virus (SIV) that vary in their levels of attenuation were tested for the ability to protect against mucosal challenge with pathogenic SIV. Four female rhesus monkeys were vaccinated by intravenous inoculation with SIVmac239Δ3, four with SIVmac239Δ3X, and four with SIVmac239Δ4. These three vaccine strains exhibit increasing levels of attenuation: Δ3 < Δ3X