FIG. 6.
Analysis of low-pH-dependent E1 conformational changes in wt SFV and H230A mutant. Purified 35S-labeled wt-ic or H230A-ic virus was preincubated with complete liposomes for 3 min at 37°C, acid treated at the indicated pH for 5 min at 37°C, returned to pH 8.0 on ice, and tested for acid-specific epitope exposure and E1 HT formation. (A) Samples were immunoprecipitated with either a polyclonal antibody against the SFV envelope proteins (Rab), a nonspecific antibody (NS), or an E1 acid-specific MAb (E1a-1) and analyzed by SDS-PAGE. Shown is a representative example of three experiments. (B) Formation of the E1 HT was determined by solubilizing samples in SDS sample buffer at 30°C and carrying out analysis by SDS-PAGE. The data shown are the average of two experiments.