Inhibition Of IBDV Replication By Gga-miR-155 Via Targeting SOCS1 And TANK

Infectious bursal disease(IBD)is an acute,highly contagious avian disease caused by IBD virus(IBDV),characterized by severe damage in the bursal of Fabricius(BF)that caused immunosuppression in young chickens.MicroRNAs(miRNAs)are a family of small,non-coding RNAs,ranging in length from 18 to 25 nucleotides,which mediate degradation of RNA and translational suppression by binding to complementary sites primarily in the 3’UTRs of mRNAs of targeted gene.miRNAs play a critical role in host-pathogen interactions,especially in innate immune response to viral infections.However the effects of miRNA in host cells on IBDV infection and the underlying mechanism have not yet been elucidated.We performed deep sequencing to examine miRNA expression profiles in DF-1 cells infected with IBDV Lx strain.Among the differentially expressed miRNAs,369 miRNAs were significantly upregulated and 169 downregulated.Twenty-two miRNAs were selected as candidates for IBDV replication analysis as they played varied roles in cancer,inflammation,and immune responses.Employing TCID50,Western Blot,IFA and real-time PCR assays,we found that transfection of DF-1 cells with gga-miR-155 markedly suppressed IBDV replication,while blockage of the endogenous gga-miR-155 by inhibitors enhanced IBDV replication.Furthermore,our data showed that gga-miR-155 enhanced the expression of type I interferon in DF-1 cells post IBDV infection.Using TargetScan and miRanda prediction softwares,we found two putative gga-miR-155 targeted genes SOCS1 and TANK(two negative regulators of type Ⅰ IFN signaling).Importantly,we confirmed that gga-miR-155 targeted SOCS1 and TANK,two negative regulators of type Ⅰ IFN signaling,exploying dual-luciferase reporter gene assay and Western Blot assays.These results indicate that gga-miR-155 enhanced type I interferon expression via targeting SOCS1 and TANK,suppressing IBDV repliaction.In summary,we found that gga-miR-155 enhanced type I IFN signaling and suppressed IBDV replication via targeting SOCS1 and TANK,two negative regulators in the immune response.These findings have revealed the molecular mechanism of inhibition of IBDV replication by gga-miR-155,and provided insights for further studies of the pathogenesis of IBDV infection.