Viral nucleic acids, including single-stranded (ss)RNA and double-stranded (ds)RNA, are sensed by RNA sensors such as TLR3 and TLRs7–9, RLRs (RIG-I and melanoma differentiation-associated gene 5 (MDA-5), or in case of viral DNA by DNA sensors such as absent in melanoma 2 and cyclic GMP–AMP synthetase (cGAS) and stimulator of interferon genes (STING) (25, 26). The gene discussed is IFIH1; the disease is melanoma.