Effect of raltegravir (RAL), alone and in combination with PMPA and FTC, on viral load (panel A) and CD4 counts (panel B) in SIVmac251-infected macaques (Group 1). SIVmac251-infected rhesus macaques (Macaca mulatta) were randomized to receive 50 (marked by the blue symbols) or 100 (red symbols) mg of raltegravir twice daily with food (bid). Monotherapy was continued for ten days. At day 11, nonhuman primates treated with 50 mg of raltegravir bid were switched to the 100 mg regimen, and two RT inhibitors, i.e. the NtRTI, tenofovir (PMPA) and the NRTI emtricitabine (FTC), were added to treatment (henceforth referred to as ART) in all animals. Viral load values positioning on the dotted line parallel to the x axis should read as undetectable.