A number of HIV-1 envelope glycoprotein oligomers have been tested for their ability to elicit neutralizing antibodies (as reviewed in [41]), and we highlight here a particularly promising soluble HIV-1 gp140 “SOSIP” variant [8,9,42-44], which is displayed with electron microscopy-determined density and modeled gp120-outer domain. Other promising HIV-1 immunogens include core HIV-1 gp120 ([45,46], outer domain gp120 (OD4.2.2) [47,48], b12-epitope scaffold [49],and b12-epitope peptide [50]••, which are shown in cartoon and semi-transparent surface representation (grey), with CD4-, VRC-PG04-, or b12-sites of binding highlighted in red. While vaccination with HIV-1 Env immunogens containing the CD4-binding site and capable of binding broadly neutralizing antibodies have in select cases elicited encouraging titers of HIV-1 neutralizing antibodies (for example, [50]••), such neutralization remains to be confirmed at the monoclonal antibody level.