Fig. 5.

Virulence and replication of rPVM and NS deletion mutants in the respiratory tract of C57BL/6 mice and B6.IFNAR^0/0 mice. C57BL/6 (A and B) and B6.IFNAR^0/0 (C and D) mice were infected intranasally with 5,000 PFU of rPVM or the ΔNS1, ΔNS2, or ΔNS1ΔNS2 mutant in an volume of 80 μl. Mice were observed closely, and body weight was monitored daily (A and C). For analyzing replication (B and D), mice were sacrificed on day 3 and day 7 after infection, and the lungs were removed, homogenized, flash frozen, and stored until use. Viral titers were determined by plaque assay. Results represent mean values and standard errors of the mean derived from a minimum of five animals per group.