The signal-to-noise ratio in the cell infection assays measuring MDA5-dependent IFN induction following EMCV infection may be limited by the induction of endogenous MDA5 expression in the parent A549 cells line (A549 RIG-I−/−ACE2−/−), such that some of the IFNB1 induction observed could be due to endogenous MDA5 rather than from the overexpressed transduced MDA5 variant. Here, RIGI is linked to infection.