Fig. 2.

Mouse-adapted RAVV VP40 exhibits enhanced ability to suppress IFN-α/β signaling in mouse cells. (A) The seven amino acid positions at which RAVV VP40 and maRAVV VP40 differ are indicated. Hepa1.6 (B) or Huh7 (C) cells were transfected with hSTAT1-GFP plasmid and empty vector (pCAGGS) or the indicated expression plasmids for FLAG-tagged viral proteins. At 24 h posttransfection, cells were treated with IFN-α/β (1,000 U/ml for 30 min) and analyzed for STAT1 phosphorylation. Total levels of STAT1-GFP were evaluated with an anti-STAT1, β-tubulin was used as a loading control, and anti-FLAG was used to assess protein expression. (D) STAT2^−/− MEFs were transfected with FLAG-mSTAT2 plasmid and the indicated plasmids. At 48 h posttransfection, the cells were treated with IFN-α/β (1,000 U/ml) for 30 min and analyzed by Western blotting for FLAG-mSTAT2 phosphorylation. Anti-FLAG antibody was used to evaluate the total levels of FLAG-mSTAT2 and viral protein expression, while anti-β-tubulin antibody was used as a loading control.