The aims of this study are to investigate the impact of the addition of maraviroc to a successful HIV-1 treatment regimen on in vitro (lymphoproliferative, ELISpot assays) and in vivo (response to subcutaneous and GI administered vaccination by antibody and skin tests as applicable) immune function, and to assess function of CD4 TFH cells by measuring cytokine and co-stimulatory protein expression in this T-cell subset.