FIG. 6.
Analysis of viral replication efficiency in the respiratory tracts of mice. Six-week-old female BALB/cJ mice (n = 3/group/time point) were inoculated intranasally with 50 μl containing 103 TCID50 of rNY1682-WT (WT), rNY1682-E158G (E158G), or rNY1682-E627K (E627K). Animals were euthanized at 12, 24, 48, and 96 h p.i. An entire lung of each animal was homogenized in 1 ml of medium and clarified by centrifugation, and nasal washes were collected from each mouse in 1 ml of medium. Viral titers of the clarified lung homogenates (A) and nasal washes (B) were determined by TCID50 assay using MDCK cells. The average of each group is shown, with error bars representing the SD. *, rNY1682-E158G had significantly higher lung titers than rNY1682-WT at all of the time points (P = 6 × 10−10; F test). **, rNY1682-E158G had significantly higher titers than rNY1682-WT in the nasal wash at 24 h p.i. (P = 0.005; F test). The dotted line (1.5 log10 units) indicates the lower limit of detection of infectious virus.