Long-term vaccine protection from AIDS and clearance of viral DNA following SHIV89.6P challenge

Abstract In an earlier study, our group vaccinated rhesus macaques with vesicular stomatitis virus (VSV) vectors expressing Gag, Pol, and Env proteins from a hybrid simian/human immunodeficiency virus (SHIV). This was followed by a single boost with modified vaccinia virus Ankara (MVA) vectors expressing the same proteins. Following challenge with SHIV89.6P, vaccinated animals cleared challenge virus RNA from the blood by day 150 and maintained normal CD4 T cell counts for 8 months. Here we report on the long-term (>5-year post-challenge) status of these animals and the immunological correlates of long-term protection. Using real-time PCR, we found that viral DNA in peripheral blood mononuclear cells (PBMCs) of the vaccinees declined continuously and fell to below detection (