FIG. 6.

WNV NS proteins induce CHOP expression and WNV growth in chop^−/− MEFs. (A) HEK293T cells were transfected with the indicated plasmids or infected with VLPs or WNV. At 42 h posttransfection/infection, total RNA was isolated and chop mRNA levels were quantitated as mentioned above. Expression of WNV E and NS5 in the transfected/infected cell lysates was verified by Western blotting. β-Actin is shown as a loading control. (B) Wild-type (wt) and chop^−/− MEFs were infected with WNV at an MOI of 1, and supernatants were collected at 24 and 48 h p.i. WNV titers were determined by plaque assay on Vero cells. Data representative of three independent experiments performed with triplicate values are shown. Data are means ± standard errors of the means. The respective P value for each sample compared with the vector alone is indicated as follows: ns, not significant (P > 0.221); **, P < 0.037; and ***, P < 0.0009. (C) Cell lysates isolated at 24 and 48 h p.i. from WNV-infected wild-type (wt) and chop^−/− MEFs were analyzed by Western blotting for CHOP, WNV NS3, and β-actin.