95 Immune Correlates in SIV L Yant, J Loffredo, T Friedrich, S Martin, D O'Connor, and David I Watkins* Wisconsin Natl Primate Res Ctr, Univ of Wisconsin, Madison, USA

Rare HIV-infected humans and simian immunodeficiency virus (SIV)-infected macaques

control viral replication and exhibit unusually good clinical outcomes. The reasons for this control are poorly understood. Typical plasma setpoint levels of SIVmac239 in Indian rhesus macaques are 1 million copies/mL, and half of the animals die within a year post-infection.

We have now followed viral replication in 171 Indian rhesus macaques, all infected with SIVmac239. Nine animals controlled replication of this highly pathogenic isolate to <500 copies/mL. Strikingly, all but two of these macaques express the Mamu-B*17 molecule, and this molecule binds an SIV-derived peptide recognized by immunodominant CD8+ T lymphocytes.

To determine the mechanism of control, we are investigating the cellular immune responses, viral escape, and viral fitness in these controllers. These unusual macaques may be a model HIVinfected long-term non-progressors, and may be useful in identifying the immune mechanisms underlying their superior viral control.