FIG. 4.

RIFA assay of mutant HAVs. Petri dish cultures of BS-C-1 cells were infected with wild-type (wt) virus (5′P2P3-18f) or with HAV mutants containing the indicated substitutions at residue 764 or 791. The inocula for the mutant viruses were lysates of infected FRhK-4 cells, collected 2 weeks after transfection with synthetic genome-length RNA. The BS-C-1 cell cultures were maintained for 1 week at 37°C before processing for detection of HAV radioimmunofoci as described in Materials and Methods.