A wide variety of cells in the body are capable of exhibiting antiviral innate immunological responses upon viral infection. Infected viruses are detected by sensory molecules, including Toll-like receptors (TLRs) and RIG-I-like receptors (RLRs: retinoic acid-inducible gene I, RIG-I; melanoma differentiation-associated gene 5, MDA5; and laboratory of genetics and physiology 2, LGP2). Whereas TLRs detect viral components in specific cells, such as dendritic cells and macrophages, RLRs sense the infected viruses in the cytoplasm of most cell types. RLRs sense viral RNA and result in immunological responses, including the production of type I interferon (IFN) and inflammatory cytokines (Akira et al., 2006, Yoneyama et al., 2005 and Yoneyama et al., 2004).