This is a multicenter study funded by the NIAID to determine the safety and immunogenicity of the candidate AIDS vaccine, HIVAC-le, a vaccine produced by recombinant vaccinia virus which expresses the envelope glycoprotein of HIV. It is a double blind randomized trial comparing the experimental vaccine with DRY-VAX smallpox vaccine as a control and a dose escalating format with subsequent boosting with a glycoprotein product.