IFIH1 and infection: Although infection of cells with CVB3 is sensitive to IFNβ (Supplemental Figure S1A), we observed less enhancement of IFNβ promoter activity as assessed by luciferase activation in CVB3-infected HEK293 cells overexpressing MAVS, MDA5, RIG-I, and TLR3/TRIF than in uninfected controls (Figure 1D).