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. 2009 Apr 15;83(13):6689–6705. doi: 10.1128/JVI.02220-08

FIG. 7.

FIG. 7.

PLP from NL63 but not MHV is an IFN antagonist. PLPs from NL63 and MHV were assayed for their ability to inhibit IFN-β, NF-κB, and STAT1 signaling in 293T cells. (A) In this assay, 293T cells were transfected with N-RIG and either GFP-, MHV PLP1-, MHV PLP2-, or NL63 PLP2-expressing plasmids and an IFN-β/luciferase reporter plasmid. At 24 h posttransfection, cells were assayed for luciferase expression. The value of induction in GFP plus N-RIG was set at 100%, with all other values in relation to it. Notice that MHV PLP1 and -2 do not block IFN-β induction, while NL63 and SARS-CoV PLP do. (B) 293T cells were transfected with GFP-, MHV PLP1-, MHV PLP2-, or NL63 PLP2-expressing plasmids and an NF-κB/luciferase reporter plasmid. At 24 h posttransfection, cells were treated with 100 ng of TNF-α; 6 h later, cells were assayed for luciferase expression. The value of induction in GFP plus TNF-α was set at 100%, with all other values in relation to it. Notice that MHV PLP1 and -2 do not block IFN-β induction, while NL63 and SARS-CoV PLP do. (C) 293T cells were transfected with either GFP-, MHV PLP1-, MHV PLP2-, or NL63 PLP2-expressing plasmids and an ISRE/luciferase reporter plasmid. At 24 h posttransfection, cells were treated with 100 ng of IFN-β; 6 h later, cells were assayed for luciferase expression. The value of induction in GFP plus IFNβ was set at 100%, with all other values in relation to it. Notice that none of the expressed proteins inhibits ISRE induction.