FIG 6.

The antiviral effect of NF-κB partially depends on its ability to trigger IFN-β expression. (A) The indicated MLE-15 cell lines were infected with SC35 or SC35M (MOI of 0.001) for 8 h. Cells were harvested, and expression of the IFN-β gene was quantified by qPCR. Error bars show SEM from three independent experiments performed in triplicate. (B) The indicated cells were infected with SC35 or SC35M (MOI of 3) for the indicated periods. Cells were harvested, and cell extracts were analyzed by immunoblotting for the occurrence and phosphorylation of IRF3 with specific antibodies. Error bars show SEM (n = 3). (C) Control cells or p65⁻ and NEMO⁻ cells were preincubated for 14 h with recombinant IFN-β at the indicated concentrations. Subsequently cells were infected with SC35 (MOI of 0.05), and virus titers were determined after 24 h p.i. The ratio between virus numbers in knockout cells and those in control cells is displayed on the y axis. Error bars show SEM (n = 3). The P values are indicated by asterisks: *, P < 0.05; **, P < 0.01. ns, not significant.