IRF3 and cytomegalovirus infection: To investigate IFN-independent ISG regulation during HCMV infection we utilized previously generated cell lines [16,39] based on the characterized abilities of the nPro protein of bovine viral diarrhea virus (BVDV) to target IRF3 (blocking IFNβ production) [44] and of the V protein of parainfluenza virus type 5 (PIV-5) to target STAT1 (blocking IFN responsiveness) [45].