NV RNA replication is sensitive to type I and III IFN treatment. (A) Effect of type I and III IFN pretreatment on NV RNA replication. 293FT cells were pretreated with increasing doses of type I (100 and 1,000 U/ml IFN-α or IFN-β) or III (10 and 100 ng/ml IL-29) IFN for 24 h and then transfected with carrier RNA (−) or NV RNA (+) and incubated for 48 h. NV VP1 in cell lysate was detected by Western blotting. Actin served as an equal loading control. (B) Effect of posttransfection IFN treatment on NV RNA replication. 293FT cells were transfected with NV RNA and treated with 1,000 U/ml IFN-β at 12 h post-RNA transfection. Cells were lysed at 48 h post-RNA transfection, and NV VP1 in cell lysate was detected by IP and Western blotting. (C) Immunofluorescence staining of NV VP1 in NV RNA-transfected 293FT cells either untreated (no IFN) or pretreated with 1,000 U/ml IFN-β. Cells were fixed at 48 h post-RNA transfection and stained with guinea pig antibody to NV VP1. Scale bars, 200 μm.