Identification Of Duck STING Gene And Its Role In Type ? Interferon Pathway

Stimulator of Interferon Genes(STING)is discovered molecule involved in anti-infection immunity.STING is recently found in mammals,and play a key role in RIG-I like receptors(RLRs)mediated signal transduction pathways.It's clear that RLRs can recognize RNA virus and activate STING,but it remains unknown whether STING exists or works in ducks.In this work,duck STING designated DuSTING was amplified via reverse transcript PCR(RT-PCR)from duck liver,its cDNA sequence contains an open reading frame of 1149 bp nucleotide encoding 382 aa protein.Sequence alignment showed that DuSTING amino acids sequence shares 44.4%,41.4% and 45.1% homology respectively with human,mice and swine,and 70.6% to chick.Bioinformatics analysis and SMART and NCBI databases were employed to elucidate that duck STING consists N-terminal trans-membrane domains and C-terminal signaling domains.Quantitative RT-PCR(qRT-PCR)of DuSTING mRNA quantification,and interferon ? promoter based IFN-? activation dual luciferase reporter assay were developed.According to qRT-PCR detection results,duSTING mRNA histology distribution in duck is different from STING in chicken.Dual luciferase reporter assays showed that over expression of duck STING activated interferon ? intensively.Domains reconstruction of duck STING genes showed that the IFN-? function was reduced when the N-terminal domains were truncated at 85-382 aa,117-382 aa and 149-382 aa of DuSTING.C-terminal of duck STING is critical,if the last 32 aa aredeleted,the function of duck STING will be abolished.The viral titer of avian influenza virus(AIV)H9N2 SH010 infected cells showed that over expression of DuSTING in DF-1 suppressed virus replication.Type I interferon genes and duck STING gene level increased when challenging AIV H9N2 SH010 and newcastle disease virus(NDV)LaSota strain.In conclusion,duck STING gene was cloned and characterized by the first time.Duck STING works in type I interferon signal transduction pathway.These results confirm that DuSTING plays a role in anti-virus innate immunity.