Figure 8.

Differential inhibition of STAT2 and STAT1 phosphorylation by HNSs transient expression and HRTV infection. A, transient expression of HNSs exclusively inhibits phosphorylation of STAT2 but not STAT1. HEK293 cells were transfected with the HNSs or HNP expression plasmids or the control vector. At 36 h posttransfection, cells were left untreated or treated with IFN-α (1000 units/ml) for 30 min. Protein levels were assessed by WB analysis with antibodies against the indicated proteins. B, HRTV infection suppresses the phosphorylation of both STAT2 and STAT1. HEK293 cells were mock-infected or infected with HRTV for 36 h and subsequently treated with IFN-α (1000 units/ml) for 30 min or left untreated. Protein levels were then analyzed by WB as in A. C and D, neither HNSs transient expression nor HRTV infection affects IFN-γ–induced STAT1 activation. Transfected (C) or infected (D) HEK293 cells were treated with IFN-γ (50 ng/ml; Peprotech) for 30 min and then subjected to WB analysis. E, effects of individual or combinatorial expression of HRTV proteins on STAT activation. HEK293 cells were transfected with the plasmids as indicated (500 ng for each viral protein expression plasmid). Total transfection amount of plasmids was kept constant by the corresponding addition of the vector. At 36 h posttransfection, cells were treated with IFN-α as in A and then delivered to WB analysis.