FIG. 8.

Effect of PKR on activation of the components of the IFN-β enhanceosome and accumulation of the C protein in HPIV1 WT and mutant virus-infected cells. (A) Stable shPKR-expressing and control shCON 293A cells were infected with WT, F170S, or P(C−) HPIV1 at an MOI of 5 for 48 h. Phosphorylated IRF3, total IRF3, total IκBβ, phosphorylated P38, total P38, and total PKR, as well as viral N, P, and C proteins were detected by Western blotting. (B) Type I IFN affects C′ protein expression during HPIV1 infection. A549 cells were infected with F170S HPIV1 at an MOI of 5. At 12 h postinfection, neutralizing antibodies against IFN-α (5,000 NU/ml) and IFN-β (2,000 NU/ml) were added. C protein was detected by Western blotting at 30 h.