FIG. 7.

IFN-β prolongs neuronal survival following WNV infection. SCG neurons from wild-type mice were infected with WNV at an MOI of 10. Neurons were either untreated (black bars) or treated 24 h prior to (gray bars) or after (white bars) infection with 100 IU IFN-β. Cells were subsequently maintained in the presence of IFN-β throughout the time course. (A) Neuronal survival was quantitated on days 4, 8, and 11 p.i. Approximately 1,000 to 2,000 cells were counted per condition in each replicate. Data are expressed relative to survival of uninfected neurons and represent the average of four independent experiments. Error bars indicate standard deviations. (B) Infectious virus production at 24 intervals following IFN-β treatment prior to or after infection was assayed on days 1 to 2, 2 to 3, 3 to 4, 7 to 8, and 10 to 11 p.i. Viral production from days 0 to 1 was assayed for IFN-β pretreatment only, as posttreatment occurred at day 1 p.i. (C) WNV antigen expression (red) was determined on day 4 p.i. by immunofluorescence microscopy. DAPI was used as a nuclear counterstain (blue). Asterisks indicate differences that are statistically significant (*, P < 0.05).