FIG. 5.

Growth of the mutants viruses. (A) Plaque morphology of the mutant viruses. MDBK cells in a 35-mm-diameter dish were infected with approximately 10² PFU of the WSN, dl12, or N110 virus, and plaques were formed for 3 days at 34 or 39°C. (B) MDBK cells in a 35-mm-diameter dish were infected with the WSN, dl12, or N110 virus at an MOI of 3. The culture was incubated for the indicated times at 34 or 39°C. Infectious viruses in the supernatant were determined by plaquing on the MDBK cells at 34°C.