To evaluate the safety and immunogenicity of HIV p17/p24:Ty-VLP (virus-like particles) vaccine in uninfected volunteers. Specifically, to determine whether the vaccine formulated with and without alum induces CD8+ cytotoxic T lymphocytes ( CTLs ) that may be cross-reactive against multiple HIV-1 stains. Also, to determine whether boosting with the vaccine orally or rectally will help induce mucosal antibody responses.