Induction of IFIT3 is STAT-2-dependent.

A549 cells were infected by mock or DV for 3, 6, and 24 h and protein levels of both phosphorylated and non-phosphorylated STAT1, STAT2, and STAT3 were analyzed by western blotting (A). Treatment with 1000 units IFN-α was used as a positive control. Expression of IFIT3 in DV-infected A549 cells with knockdown of either STAT2 (B), STAT1 (C) or STAT3 (D) was determined by western blotting (B, C, and D) or quantitative RT/PCR (B). Both shRNA and siRNA were used as the approaches for STAT1/STAT2 and STAT3, respectively, as described in Materials and Methods. Knockdown with shGFP or si-Ctl was used as a negative control. Data show representative results and analysis pooled from at least 3 independent experiments. The analysis was performed by ANOVA as described in Materials and Methods. **P < 0.01. Ctl stands for control.