Effect of low pH treatment on the oligomeric conformation of mutant gB with elevated fusion activity. (A) Reactivity of oligomer-specific monoclonal antibody DL16 with low pH-treated HSV-1 ANG path virions. As in Figure 1, virions were treated with pHs ranging from 7.4 to 5.2, and were blotted to membrane. Blots were probed at neutral pH with trimer-specific MAb DL16. (B) The indicated virions were treated with pHs ranging from 7.4 to 5.2, solubilized with 1% SDS, and then analyzed by "native" PAGE. Immunoblots were probed with gB-specific polyclonal antibody. Panel shows the major gB species, which migrate slower than a 181 kilodalton protein standard (not shown).