DDX3, a cytoplasmic helicase that recognizes RNA in cytoplasm of myeloid cells. RNA viruses replicate the RNA to form a double‐stranded structure. DDX3 senses the replicative RNA to activate the MAVS (mitochondrial antiviral signaling) pathway, which in turn induces antiviral response, including type I IFN. Tsukasa Seya MD, PhD (Department of Microbiology and Immunology, Hokkaido University Graduate School of Medicine)