Fig 3.

Anti-MPER IgG titers in New Zealand White rabbits immunized with side chain-modified MPER lipopeptides. (A) Antibody responses directed against the immunizing epitope. Antibody responses against N-MPER(T-PO₃) were significantly increased at days 94 and 115 over those on day 0 (P < 0.05), while other modifications failed to induce a significant response. Average antipeptide reciprocal endpoint titers are calculated at each day and normalized to day 0 preimmune titers. Responses are shown as the fold change over day 0 preimmune titers. (B) Antibody responses from rabbits at day 115 elicited by their respective lipopeptides. Antibody responses to N-MPER(T-PO₃) were significantly different from those to all other lipopeptides (P < 0.05). (C) Antibody responses from rabbits with high titers tested against all other immobilized immunogens at day 115. Rabbit sera showed strong responses toward 2F5 epitopes with and without S668 phosphorylation but lacked responses toward modified and unmodified 4E10 epitopes.