FIG. 2.

VRP and VEEV infection disrupts the nuclear localization of STAT1 in response to IFN. Vero-81 cells were infected for 6 h with VRP at an MOI of 5 IU/cell (A and C) or for 5 h with VEEV 3014 at 10 PFU/cell (B) and then stimulated with IFN-γ or IFN-β for 20 to 40 min (200 to 1,000 U/ml). Subcellular extracts were prepared and analyzed by Western blotting to determine total STAT1 distribution (A and B). GRP 78, a protein found within the endoplasmic reticulum, verifies the purity of the nuclear fractions. In an indirect immunofluorescence staining assay (C), cells were fixed after IFN treatment and stained for total STAT1 protein. Infected cells expressing GFP and STAT1 subcellular distribution (red) were detected by confocal microscopy and demonstrate the nuclear redistribution of STAT1 in uninfected cells but not in VRP-infected cells.