Study Design: This is a Phase I, randomized, placebo-controlled, double-blinded study to examine safety, tolerability and immune response of a prime-boost vaccination regimen for treatment of HIV infection. The vaccination schedule consists of three injections of a multiclade HIV plasmid DNA vaccine followed by one injection of a multiclade recombinant adenoviral vector vaccine (rAd), in HIV-infected adults. The hypothesis is that this vaccination regimen will be safe and elicit an immune response in HIV-infected subjects. The primary objectives are related to evaluating the safety and tolerability of the vaccination regimen and assessing the effect of vaccination on humoral and cellular immune responses to vaccine-specific HIV antigens.