Experiments with RIG-I-, MDA5-, and RIG-I/MDA5-deficient mouse fibroblasts showed that RIG-I is the critical pattern recognition receptor needed for the influenza B virus-induced activation of IRF3.
Collectively, although Mda5 is functionally active in the chicken, the absence of an apparent RIG-I-like function may contribute to the chicken's susceptibility to highly pathogenic influenza.