This invention relates to fusion polypeptides comprised of a trimerization domain fused to a non-membrane bound, non-cleaved gp160 polypeptide derived from the R2 HIV-1 Env glycoprotein and to compositions comprising the fusion polypeptides. This invention further relates to oligomers of the fusion polypeptides. This invention also relates to nucleic acids encoding the fusion polypeptides. This invention also relates to diagnostic and therapeutic methods using the fusion polypeptides. Further, this invention relates to the induction of cross-reactive neutralizing antibodies against HIV-1, and to immunogenic compositions for the prevention and treatment of infection by HIV-1.
