Development of a tier 1 R5 clade C simian-human immunodeficiency virus as a tool to test neutralizing antibody-based immunoprophylaxis

Background While some recently transmitted HIV clade C (HIV-C) strains exhibited tier 1 neutralization phenotypes, most were tier 2 strains (J Virol 2010; 84:1439). Because induction of neutralizing antibodies (nAbs) through vaccination against tier 2 viruses has proven difficult, we have generated a tier 1, clade C simian-human immunodeficiency virus (SHIV-C) to permit efficacy testing of candidate AIDS vaccines against tier 1 viruses. Methods SHIV-1157ipEL was created by swapping env of a late-stage virus with that of a tier 1, early form. Results After adaptation to rhesus macaques (RM), passaged SHIV-1157ipEL-p replicated vigorously in vitro and in vivo while maintaining R5 tropism. The virus was reproducibly transmissible intrarectally. Phylogenetically, SHIV-1157ipEL-p Env clustered with HIV-C sequences. All RM chronically infected with SHIV-1157ipEL-p developed high nAb titers against autologous as well as heterologous tier 1 strains. Conclusions SHIV-1157ipEL-p was reproducibly transmitted in RM, induced cross-clade nAbs, and represents a tool to evaluate anti-HIV-C nAb responses in primates.