Figure 3. Pathogenicity of SC_WT, SC_PA-A36T, and SC_PB2-H357N viruses in mice.

Six-week-old female BALB/c mice (n = 5/group) were inoculated intranasally with 50 µl containing 10⁴ TCID₅₀ of the recombinant viruses SC_WT, SC_PA-A36T, and SC_PB2-H357N, or PBS (mock). (A) Morbidity was assessed by weight changes over a 14-day period and is graphed as a percentage of the average weights on the day of inoculation (day 0). The average body weight change of each group is shown with error bars representing SEM (+/−). (B) Mortality associated with infection with the recombinant viruses SC_WT, SC_PA-A36T, and SC_PB2-H357N was also examined.