Caspase-8 and FLIP regulate RIG-I/MDA5-induced innate immune host responses to picornaviruses.

Picornaviruses are small, nonenveloped, positive-stranded RNA viruses, which cause a wide range of animal and human diseases, based on their distinct tissue and cell type tropisms. Myocarditis, poliomyelitis, hepatitis and the common cold are the most significant human illnesses caused by picornaviruses. The host response to picornaviruses is complex, and the damage to tissues occurs not only from direct viral replication within infected cells. Picornaviruses exhibit an exceptional ability to evade the early innate immune response, resulting in chronic infection and autoimmunity. This review discusses the detailed aspects of the early innate host response to picornaviruses infection mediated by RIG-I-like helicases, their adaptor, mitochondrial ant iviral signaling protein, innate immune-induced apoptosis, and the role of caspase-8 and its regulatory paralog, FLIP, in these processes.