RIGI and COVID-19: Following the cell entry, the host pattern recognition receptors (PRRs), such as retinoic acid-inducible gene-I protein (RIG-I), melanoma differentiation-associated gene 5 (MDA5) and Toll-like receptor (TLR) recognize the virus, wherein the viral E protein induces TLR-2, which alleviates the innate immune activation in COVID-19 patients (37).