FIG. 4.

Low-pH conformational changes affect MAb epitopes. Side-by-side surface views of domains I and V of the wt-gB-neutral (A) and W714R-acidic structures (B) (bottom panels) and an enlarged view of the H126 epitope in these structures (top panels). Regions are colored by epitope, and FL2 is colored orange. The side chain of H308 is shown as yellow sticks. The nearby Y303 side chain is shown in purple. Y303N is the MAb resistance mutant (mar) for the H126 neutralizing antibody. Views in panel A and B are shown in the same orientation, obtained by superposing the entire W174R-acidic trimer onto the wt-gB-neutral trimer.