FIG 1.

Characterization of a STAT2blind V protein without alteration of the P open reading frame (Porf). (A) Nucleotide and P- and V-protein sequences of the STAT2-binding region. STAT2-binding residues are indicated in boldface type, and the corresponding nucleotide sequence is shown in italic boldface type. Mutations that alter the V-protein sequence while maintaining the P-protein sequence are shown in gray. C245 is not conserved and may not be used to complex zinc. (B to D) IFN signaling interference activity of the V-protein mutants. Huh7 cells were transfected with either a GAS-luciferase reporter gene plasmid (B), ISRE-luciferase reporter gene plasmid (C), or IFN-β–luciferase reporter gene plasmid (D) in combination with either an empty vector, or vectors expressing the CDV wild-type (WT) V protein, or the respective mutant CDV V proteins as indicated. The cells were treated with 100 ng/ml of IFN-γ or 1,000 U/ml of IFN-α or transfected with 1 μg/ml of poly(I·C) for 18 h, 8 h, or 20 h prior to lysis, respectively, and luciferase activity was measured. Luciferase activity of cells transfected with an empty vector was set at 100%. Values are the averages of three experiments done in triplicate; error bars indicate the standard errors of the means (SEM).