Study of the Antiviral and Immunological Effects of Intensification of Suppressive Antiretroviral Therapy With Maraviroc

"ARM A:~Addition of maraviroc to baseline ARV medications for 24 weeks at one of the following doses:~* 150 mg orally BID when coadministered with a ritonavir-boosted protease inhibitor~* 600 mg orally BID when coadministered with efavirenz or nevirapine~ARM B:~Addition of an additional NRTI to baseline ARV medications for 12 weeks then cross over to maraviroc intensification for an additional 12 weeks as above:~* Addition of abacavir 600 mg orally once daily to a tenofovir containing regimen for 12 weeks then replacing the abacavir with maraviroc.~* Addition of an alternate FDA approved NRTI \[such as zidovudine (AZT) or didanosine (ddi)\] at standard oral dosing to a tenofir containing regimen for 12 weeks (if the participant declines abacavir therapy) then replacing the alternate NRTI with maraviroc.~* Addition of tenofovir 300 mg daily to an abacavir containing regimen for 12 weeks then replacing the tenofovir with maraviroc."