FIG. 3.
NF-κB is essential for delNS1 virus-induced IFN-β gene expression. (A) Monolayers of 293 cells were cotransfected with pIFN-CAT (encoding a CAT reporter gene under a mouse IFN-β promoter) and a plasmid expressing a superrepressor form of IκB, IκB(SA), or empty vector. One day posttransfection, cells were mock treated or transfected with 50 μg of dsRNA or infected with PR8, delNS1, or NDV viruses at an MOI of 1. One day later, CAT assays were performed with 5 μl of cell extracts. (B) Quantitative analysis of the results shown in Fig. 3A. (C) Monolayers of 293 cells were cotransfected with pIFN-CAT and a plasmid expressing a dominant-negative form of IκB kinase, IKKβ(KA), or empty vector. One day posttransfection, cells were treated as in panel A. Quantitative results are indicated. (D) 293 cells were transfected with a plasmid expressing IκB(SA) or empty vector. One day posttransfection, cells were infected with PR8, delNS1, or Sendai viruses at an MOI of 1 for the indicated times. RNAs were extracted and subjected to Northern blot analysis with probes specific for IFN-β and β-actin mRNAs.