Fig 4.

vIRF1 expression inhibits IRF3 downstream of TLR3. (A) 293 and 293-TLR3 cells were transfected with the control vector or vectors expressing vIRF1, -2, or -3. Twenty-four hours posttransfection, cells were treated with poly(I·C) for 16 h before cells were harvested, lysed, and subjected to immunoblotting. (B) 293-TLR3 cells were transfected with the control vector or vectors expressing vIRF1, -2, or -3, and 4 h posttransfection, cells were trypsinized and moved to 6-well dishes containing coverslips. Twenty hours after replating, cells were treated with poly(I·C) for 1 h before coverslips were harvested and stained for IRF3 (shown in green). DAPI staining is shown in blue. Arrows point to vIRF-expressing cells. (C) 293-TLR3 cells were transfected with a control vector or vIRF1, -2, or -3 and cotransfected with control vector or cellular IRF3. One day posttransfection, cells were treated with poly(I·C) for 24 h before supernatants were harvested and subjected to IFN-β ELISA. Values represent the means plus or minus the standard deviations of the means of results from triplicate samples. *, P < 0.05; **, P < 0.04; and ***, P < 0.01 (by Student's t test).