There are currently several Phase I and II clinical trials being performed within AVEG to evaluate different HIV-1 vaccine candidates. The HIV-1 vaccination approach that is furthest along the clinical development pathway is the so-called prime-boost regimen of live recombinant canarypox priming (ALVAC-HIV vCP205) with recombinant subunit protein boosting (HIV-1 SF-2 rgp120 in MF59 adjuvant). The protein boost enhances neutralizing antibody responses against laboratory strains of HIV-1 in assays performed in vitro, as well as enhancing CD4 cell response and increasing the frequency of CD8 cytotoxic T lymphocytes (CTLs). In all of the ALVAC-HIV trials of the prime-boost regimen completed to date, the protein boost has been the HIV-1 SF-2 rgp120 subunit protein. This study is designed to explore whether boosting of live recombinant canarypox vaccination with a novel protein subunit, recombinant HIV-1 SF-2 p24, can enhance the CD4 and CD8 cell responses directed against HIV-1 antigens.