FIG 4.

IFN-β transcription was monitored following infection of control, MAVS-depleted, or RIG-I-depleted 293 cells at 24 h postinfection with either wild-type KSHV or UV-inactivated KSHV. Both MAVS-depleted and RIG-I-depleted 293 cells showed decreased amounts of IFN-β transcripts compared to that in the control at 24 (A) and 48 (B) h postinfection. MAVS or RIG-I knockdown in 293 cells infected with UV-inactivated KSHV resulted in no induction of IFN-β transcription, indicating a requirement for infectious virus particles for stimulation of type I IFN.