Functional Characterizations Of IPS-1to GCRV And Viral/bacterial Analogues In Grass Carp Ctenopharyngodon Idella

Grass carp (Ctenopharyngodon idella) is an important freshwater species in China, butthe hemorrhagic disease caused by grass carp reovirus（GCRV）impacts on the developmentof aquaculture industry. Grass carp is lower vertebrates and the innate immune has importantplace in immune systerm of grass carp, therefore, investigating the antiviral regulatorymechanism of immune genes will lay a foundation for the therapeutic strategies of hemorragicdisease.IPS-1(IFN-β promoter stimulator1, IPS-1) is a unique adaptor of RLRs (retinoicacid-inducible gene-I (RIG-I)-like receptors, RLRs) family and plays an important role inRLRs-mediated antiviral immunity. Grass carp IPS-1(CiIPS-1) protein contains anN-terminal CARD (caspase activation and recruitment domain, CARD), a central proline-richdomain (PRO), a putative TRAF2-binding motif and a C-terminal transmembrane domain. Inmammals, studies have shown that IPS-1can recruit many downstream immune-related genesto participate in antiviral immune responses, but in teleosts, little is known about themechanism of IPS-1mediated antiviral immune responses. The results were as follows:1．CiIPS-1could activate the downstream genes including IRF3/7, IFN-I, Mx1and IL-1βpost virus infection or PAMPs (pathogen-associated molecular patterns, PAMPs) stimulation.In addition, CiIPS-1would get precedence for activation of IRF3contrasted with IRF7.2. In the course of immunity, CARD of CiIPS-1was responsible for receiving andtransmitting the signals, and also it was important for the activation of early signals; TM andTRAF were required for the activation of IRF3, IRF7, IFN-I and Mx1; PRO maybe regulatedthe signaling pathways mediated by CiIPS-1; besides, PRO and TRAF were necessary for theinduction of IL-1β mediated by activation of NF-κB (nuclear factor-κB, NF-κB), and CARDwas also an inducer of IL-1β.3.96-well plate staining assay, virus titer test and viral quantities all showed CARD, TM,TRAF motif were important to CiIPS-1-mediated antiviral signaling.4. The analysis indicated CiIPS-1could induce antiviral state based on coordinating the IRF3/7and NF-κB by its domains after viral infection or PAMPs simulation.