Immunogens based on an hiv-1 v1v2 site-of-vulnerability

An epitope-scaffold protein, comprising:

• (A) a gp120 polypeptide, comprising:
• gp120 positions 126-196 according to the HXB2 numbering system and corresponding to the amino acid positions in the amino acid sequence set forth as SEQ ID NO:
• 1;
• a first pair of cross-linked cysteines at positions 126 and 196, and a second pair of crosslinked cysteines at positions 131 and 157;
• a first N-linked glycosylation site comprising an asparagine residue at position 160 and a second N-linked glycosylation site comprising an asparagine residue at position 156 or position 173, wherein the first and second glycosylation sites are glycosylated;
• and
• (B) a heterologous scaffold comprising a 1VH8 scaffold;
• wherein
• the 1VH8 scaffold is linked to the gp120 polypeptide, and the epitope scaffold protein specifically binds to monoclonal antibody PG9.