FIG. 1.

Determination of lung virus titers over a 9-day period for WT (■) and STAT1−/− (▵) CD1 mice inoculated i.n. with WSN and PR8 viruses. (A) Animals of each genotype were inoculated i.n. with 1,000 PFU (1 LD₅₀ for a WT animal) of WSN virus in 50 μl of PBS. Four to five WT and STAT1−/− animals were sacrificed at each time point. Results from two experiments are included. Viral titers in lung homogenates from each animal (PFU/gram of tissue) were determined by plaque assay in MDCK cells. (B) Fifteen animals of each genotype were inoculated i.n. with 10 TCID (1 LD₅₀ for a WT animal) of PR8 virus in 100 μl of PBS. Five WT and five STAT1−/− animals were sacrificed at days 3, 6, and 9 p.i. Viral titers in lung homogenates from each animal were determined as TCID/milliliter.