Figure 6. Envelope glycoprotein reactivity immunized rabbit sera.

(A–C) Endpoint titers for Env-binding IgG reactivity from bleeds 2–4 (panel A = bleed 2, panel B = bleed 3, panel C = bleed 4). Sera were collected 7 days after the 2^nd, 3^rd and 4^th immunizations, serially diluted 5-fold, and analyzed by IgG ELISA against immobilized gp140 oligomers. End-point ELISA titers were defined as the last reciprocal serum dilution at which the optical density signal was greater than two-fold over the signal detected with the preimmune serum. Dots denote end-point titers for individual animals, while horizontal lines denote mean end-point titers for all 4 animals in each group.