Pilot Study on the Effect of Adding Raltegravir +/- a Second Drug on HIV Levels in the Gut

The "PLUS" study is a pilot study to measure the effect of therapy intensification (with raltegravir and optional second agent) on HIV levels in the gut and blood in patients on antiretroviral therapy (ART) with viral load \< 50 copies/mL (herein referred to as "suppressed"). We hypothesize that there is ongoing replication in the gut despite suppressive ART and that this replication can be inhibited by the addition of one or two new antiretroviral drugs whose activity affects a distinct part of the viral life cycle. All study participants will have upper and lower endoscopy at baseline (before intensification) and after intensification. These endoscopies will be used to obtain gut tissue and single cells (for CD4+ cells) .