Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Influenza C virus NS1 protein counteracts RIG-I-mediated IFN signalling | Pachler and Vlasak Virology Journal 2011 8 48 http content 8 1 48 J VIROLOGY JOURNAL SHORT REPORT Open Access Influenza C virus NS1 protein counteracts RIG-I-mediated IFN signalling Karin Pachler Reinhard Vlasak Abstract The nonstructural proteins 1 NS1 from influenza A and B viruses are known as the main viral factors antagonising the cellular interferon IFN response inter alia by inhibiting the retinoic acid-inducible gene I RIG-I signalling. The cytosolic pattern-recognition receptor RIG-I senses double-stranded RNA and 5 -triphosphate RNA produced during RNA virus infections. Binding to these ligands activates RIG-I and in turn the IFN signalling. We now report that the influenza C virus NS1 protein also inhibits the RIG-I-mediated IFN signalling. Employing luciferase-reporter assays we show that expression of NS1-C proteins of virus strains C JJ 50 and C JHB 1 66 considerably reduced the IFN-b promoter activity. Mapping of the regions from NS1-C of both strains involved in IFN-b promoter inhibition showed that the N-terminal 49 amino acids are dispensable while the C-terminus is required for proper modulation of the IFN response. When a mutant RIG-I which is constitutively active without ligand binding was employed NS1-C still inhibited the downstream signalling indicating that IFN inhibitory properties of NS1-C are not necessarily linked to an RNA binding mechanism. Background Innate immune response is the first unspecific defence against viral infections in which the induction of type I IFNs is essential for controlling influenza virus replication and spread. Recently RIG-I has been identified as the major cytosolic pattern-recognition receptor sensing RNA in influenza virus-infected cells thereby initiating the IFN signalling 1 2 . RIG-I which belongs to the DExD H box family of RNA helicases consists of two N-terminal caspase activation and recruitment domains CARDs an internal ATP-dependent RNA helicase domain and a C-terminal repressor
