FIG. 4.

Characterization of KUN virus containing a Thr-to-Pro compensatory mutation at codon 149 that rescues the packaging defect caused by NS2A-I59N mutation. (A) Plaque morphology of WT and mutant viruses. BHK21 and VERO cells were infected with the viruses at a multiplicity of infection of 0.1 PFU/cell and stained with crystal violet at 4 and 5 days postinfection, respectively. (B and C) Growth kinetics of the WT and mutant viruses on BHK21 and VERO cells, respectively. Culture fluids from infected cells were collected every 12 h for 3 days, and viral titers were determined by plaque assay as described in Materials and Methods.