Fig 4.
Replication of PA mutant viruses lacking N-truncated PAs in the lungs of mice. Eight groups (n = 10 per group) of 6-week-old female BALB/c mice were infected intranasally with 102 PFU of virus, and 3 and 6 days later, lungs were collected for virus titration. Each bar represents the mean titer for each virus. The data are the mean titer and the SD for each virus. An asterisk indicates that the mean titer of the PA mutant virus was significantly lower than that of the wild-type WSN (P < 0.05). Detection limit, 2 log10 PFU/g tissue.