We have previously shown that NSs inhibits IFN-β expression immediately after infection with the virulent RVFV strain ZH548 (ZH), without inhibiting IFN-β-specific transcription factors such as IRF3, NF-κB and ATF2 that are normally activated and translocated to the nucleus in RVFV-infected cells [26]. Here, IRF3 is linked to infection.