Fig 6.

Effects of histidine substitutions in RVFV glycoproteins on the formation and stability of the Gc oligomer. (A) Equal amounts of wild-type and mutant RVFV_ns particles were exposed for 10 min to pH 5.5 at 37°C, returned to neutral pH, heated for 20 min at the indicated temperatures, and subsequently analyzed by Western blotting (nonreducing conditions) using a polyclonal antiserum raised against the Gc ectodomain (Gce). In some cases, Gc runs as a closely spaced doublet. The thermostability of the acid-induced Gc oligomer is indicated for the wild-type and Gn- and Gc-His mutant RVFV_ns particles at 20°C and 80°C (left) or for the wild-type and the Gc-His mutant RVFV_ns particles at 40°C, 70°C, and 80°C (right). (B) Equal amounts of wild-type and mutant RVFV_ns particles containing histidine-to-alanine mutations in Gc were exposed to pH 5.5 at 37°C for the indicated times and analyzed by Western blotting (nonreducing conditions) using a polyclonal antiserum raised against the Gc ectodomain. OC, oligomeric complex; WT, wild-type. (C) Equal amounts of wild-type and H857A mutant RVFV_ns particles were exposed for 10 min at 37°C to the indicated pH. The Gc conversion was analyzed by Western blotting as described for panel B.