[Cell type specific involvement of RIG-I in antiviral responses].

Toll-like receptors (TLRs) play an important role in antiviral response by recognizing viral components. Recently, a RNA helicase, RIG-I, is also suggested to recognize viral double-stranded RNA. However, how these molecules contribute to viral recognition in vivo is poorly understood. Here we would like to show that RIG-I is essential for induction of type I interferons (IFNs) after infection with RNA viruses in fibroblasts and conventional dendritic cells (DCs). RIG-I induces type I IFNs by activating IRF3 via IkappaB kinase related kinases. In contrast, plasmacytoid DC, which produce large amounts of IFN-alpha, use the TLR system rather than RIG-I for viral detection. Taken together, RIG-I and the TLR system exert antiviral responses in a cell type specific manner.