FIGURE 8.

Silencing of Cdc42 or ARHGAP21 has significant effects on influenza A virus replication. A, A549 cell lines stably expressing the shRNAs targeting either Cdc42, ARHGAP21, or control luciferase were infected with A/WSN/33 influenza virus at multiplicity of infection of 0.05. The supernatants of cell culture were harvested and examined for the viral titers by hemagglutinin assay at different time points post-infection as indicated. B and C, Cdc42 knockdown A549 cells, ARHGAP21 knockdown A549 cells, and control cells were infected with influenza A virus as described in A. Viral titers in the supernatants of these cells were examined by plaque assay (post-infection = 24 h) in Madin-Darby canine kidney cells. B, shown are representative of plaques formed by influenza A virus and stained with 0.165 mg/ml neutral red. C, the average viral titers from three independent experiments are plotted. The error bars represent the S.E. (n = 3; *, p < 0.01; **, p < 0.005). PFU, plaque-forming units.