FIG. 7.

Surface expression of IFNGR1 subunits is moderately reduced in VRP-infected cells. Vero-81 cells were infected with mock or VRP (MOI = 5) for 6 h, which resulted in the infection of 98.8% of cells as determined by an indirect immunofluorescence staining assay that detects the viral nonstructural proteins (data not shown). (A) Mock- or VRP-infected cells were pooled, counted, and then separated into replicate groups for staining. Cells were either stained with anti-CD119 (IFNGR1) directly conjugated to phycoerythrin (solid line) or left unstained (shaded histogram). Cells in each group were then washed, fixed, and analyzed by flow cytometry. Mean fluorescence intensities (MFI) of mock- and VRP-infected samples were compared, and the decrease in IFNGR1 surface expression was comparable between three independent experiments (10 to 18% decrease). (B) Mock- and VRP-infected cells in parallel cultures were stimulated with 1,000 U of IFN-γ/ml for 20 min and harvested and analyzed as described in Fig. 3 to measure the inhibition of STAT1 phosphorylation.