MX1 and infection: In fish, similar to higher vertebrates, the viral nucleic acids are recognized by pattern recognition receptors like Rig-like helicases (Rig-I, MDA5) leading to signaling cascades and production of type I IFN and cytokines followed by induction of interferon-stimulated genes (ISGs) such as MX-1 with antiviral roles to clear infections [59,60,61,62].