FIG. 2.

Homologous and heterologous neutralizing antibody responses against pseudotyped viruses made with the four env variants used as the basis for immunogen design. The ability of a 1:20 dilution of rabbit serum samples to neutralize the pseudoviruses shown at the top following DNA priming and gp140 boosting is indicated along the y axis. Each point represents the immune response by an individual rabbit, with six rabbits per immunogen. The immunogen is indicated along the bottom x axis. Homologous responses are highlighted by the gray bars. Fifty percent neutralization is indicated by the dotted horizontal line.