In this study the safety, tolerability, and immunogenicity of a recombinant MVA-BN® vaccine expressing cytotoxic T lymphocyte (CTL) and helper T lymphocyte (HTL) epitopes of HIV-1 (MVA-mBN32) in 36 healthy volunteers will be examined. This will include a full analysis of CD4+ T helper cells and CD8+ CTL responses to these epitopes, to establish the potential of such a homologous prime-boost vaccine approach to induce a broad cell-mediated response to different HIV antigens.