Mammalian Reovirus μ1 Protein Inhibits IRF3 Regulating The Role Of Type Ⅰ Interferon Signaling Pathway

Mammalian reovirus is a non-enveloped gene segmented double-stranded RNA virus.This virus infection is common in mammals and can cause severe respiratory and gastrointestinal diseases and encephalitis in humans and animals,which has potential harm to human and animal health and public health.However,there are few researches on this virus,especially its infection mechanism and immune escape.In this study,mammalian reovirus μ1 protein was used as the research object to explore the role and mechanism of μ1 in the regulation of interferon signaling pathway,laying a theoretical foundation for anti-MRV infection.Results obtained in this study:1.By TCID50 detection,μ1 protein significantly promoted the proliferation of MRV in vitro.Through q PCR and Western Blot analysis,μ1 protein inhibited MRV-induced IFN-β m RNA transcription and RLRs signaling pathway protein expression.2.Poly(I:C)stimulant and MRV were used to stimulate and activate the RLRs signaling pathway.Fluorescence q PCR detection showed that μ1 protein significantly inhibited the production of Poly(I:C)and IFN-β induced by MRV.Meanwhile,Western Blot and IFA tests showed that μ1 protein significantly inhibited the phosphorylation and nuclear shift of MRV-activated IRF3,demonstrating that μ1could inhibit the RLRs signaling pathway.3.By fluorescence q PCR detection,μ1 protein significantly inhibited IFN-βinduced by RIG-I,MDA5,MAVS,TBK1,and IRF3 in the RLRs signaling pathway.Western Blot analysis showed that μ1 protein inhibited the expression of five key proteins in the RLRs signaling pathway,thus inhibiting the activation of RLRs signaling pathway and IFN-β production.4.cO-IP and Western Blot showed that μ1 protein interacted with five key proteins in the RLRs pathway.There was no interaction with STING negative control in the c GAS-STING pathway of DNA virus signaling pathway.The results show thatμ1 inhibits or blocks the RLRs signaling pathway through targeted interactions with five key signaling pathway proteins.Taken together,this study demonstrates for the first time that structural proteinμ1 of MRV virus infects host cells by interacting with the RLRs signaling pathway proteins RIG-I,MDA5,MAVS,TBK1,and IRF3,and by inhibiting IRF3 phosphorylation,nuclear shift,and nuclear entry levels.Thus,it can inhibit the activation of RLRs signaling pathway and further inhibit the production of IFN-β.This study revealed the important mechanism of MRV μ1 structural protein antagonizing type I interferon signaling pathway and realizing virus escape,which laid an important foundation for further study of virus mechanism and development of prevention and control technology.