Symptomatic infection is also linked to several variations in the interferon regulatory factor 3 (IRF3) gene (a regulatory factor of interferon), and Myxovirus resistance 1 (Mx1) which encodes for an IFN-inducible guanosine triphosphate protease (GTPase) with antiviral gatekeeper properties [150]. This evidence concerns the gene IRF3 and infection.