FIG 10.

Replication of pH1N1 LAIV viruses in mouse lungs. Six- to eight-week-old female C57BL/6 mice (n = 9) were infected i.n. with 1 × 10³ PFU of the indicated pH1N1 LAIV viruses. (A) Viral replication in the lungs of infected mice was evaluated at 1, 3, and 5 days p.i. (dpi) (n = 3) by immunofocus assay using an anti-NP MAb (HB-65). Symbols represent data from individual mice. Bars represent the geometric means of lung viral titers. The dotted line represents the limit of detection of the assay (200 FFU/ml). *, P < 0.05 using Student's t test (n = 3 per time point) from Microsoft Excel. (B) mRNA expression levels of the viral M1 in lungs of infected mice were quantified by RT-qPCR analysis. Fold expression changes in each mouse group were calculated relative to the control group of mock (PBS)-infected mice. Data represent the averages and SD values for three mice in each group on the days indicated.