• Average viral load among participants in both placebo and raltegravir arms [ Time Frame: At Week 10 and Week 12 (or the last 2 scheduled evaluations after Week 8 and before switching regimens) ] [ Designated as safety issue: No ]
  

• Viral load [ Time Frame: At baseline, Weeks 10/12 (average), and Weeks 22/24 (average) ] [ Designated as safety issue: No ]
  
• CD4 count [ Time Frame: at baseline, Week 12, and Week 24 ] [ Designated as safety issue: No ]
  
• Level of CD4+ T-Cell activation [ Time Frame: at baseline, Week 12, and Week 24 ] [ Designated as safety issue: No ]
  
• Level of CD8+ T-Cell activation [ Time Frame: At baseline, at Week 12, and Week 24 ] [ Designated as safety issue: No ]
  
• Adverse Events related to study treatment [ Time Frame: From randomization to Week 12, and Week 12 to Week 24 ] [ Designated as safety issue: Yes ]
  
• Proportion of subjects who discontinue raltegravir [ Time Frame: Prior to Week 12 and 24 ] [ Designated as safety issue: No ]
  

Although ART has reduced the morbidity and mortality from HIV-1 infection, most individuals who stop ART experience rapid viral rebound. Effective ART can suppress viral load to less than 50 copies/ml; however, current treatment regimens can not completely eliminate the infection. The primary purpose of this study is to assess the ability of the HIV-1 integrase inhibitor, raltegravir, to reduce viral load when added to ART regimens of HIV-1 infected patients who have achieved viral suppression to less than 50 copies/ml.

The study will last 24 weeks. Participants will be randomly stratified to one of two arms. Participants in Arm A will be administered raltegravir in addition to their usual ART regimen from study entry until Week 12. At Week 12, subjects will halt raltegravir use and receive a placebo until Week 24. Participants in Arm B will be administered the placebo in addition to their usual ART regimen from study entry until Week 12. At Week 12, subjects will halt the placebo and receive raltegravir until Week 24. A real-time polymerase chain reaction (PCR) single copy assay (SCA) capable of detecting 1 copy/ml of HIV RNA will be used to assay viral load. The cross-over design allows assessment of the effect of intensification with raltegravir between the two arms at Weeks 10 and 12 and assessment of viral rebound after discontinuation of raltegravir in Arm A.

All participants will have scheduled visits at Weeks 0, 2, 4, 10, 12, 14, 16, 22, and 24. A targeted physical exam and blood and urine collection will occur at all visits. A medical/medication assessment will occur at trial entry. Drug dispensing and an adherence questionnaire will occur at some visits. A pregnancy test will occur at select visits. Participants' current ART medications will not be provided by the study.