FIG 3.

N-terminal residues 114 to 140 are necessary for efficient NiV P, V, and W inhibition of STAT1 and STAT4 activity. (A and B) HEK293T cells were transfected with an ISG54-promoter firefly luciferase reporter (A) or a STAT4-response element (STAT4RE) firefly luciferase reporter (B), constitutively expressed Renilla reporter and the indicated NiV P, V, or W wild-type (WT), the 114-140 deletion mutant (Δ), or a G121E point mutant (121) expression plasmid. E, empty vector control. Transfected cells were treated with IFN-β or IFN-γ, as indicated. At 24 h posttreatment, the firefly luciferase activity was normalized to the Renilla luciferase activity, and the fold increase over mock treatment was determined. Error bars represent standard errors of four transfections performed in parallel. The experiment was performed three times. Statistical significance was determined by using a two-tailed t test for the indicated samples (****; P < 0.0001). NiV protein expression was confirmed by Western blotting with anti-HA and anti-GAPDH. IB, immunoblot.