As shown in Figure 5A, expression of IRF7 in HEK293 cells led to the induction of the IFNα4 promoter linked to a luciferase reporter gene, which was further increased by infection with Sendai virus (SV), a ssRNA virus known to induce the RIG-I-IRF7 signaling pathway [25], [26]. Here, IRF7 is linked to infection.