A Large-scale RNAi Drosophila Screening For DCV Infection Identifies That Nipped-A Regulates Viral Infection Through The DSTING Signaling Pathway

BackgroundRecently,the virus induced infectious disease has become increasingly significant to human society medically and economically.Viruses are easy to mutate,which makes the development of a specific cure becomes especially difficult.The existed vaccines could only cover limited number of known viruses.There are still large gaps for many medically significant viruses.The successful development of a vaccine against a newly identified virus is time costing with no guarantee.This is far from meeting the urgent needs for a sudden outbreak pandemic.On the other hand,in the long battle history between virus and host,the host must develop mechanisms that are effective for defensing itself.Understanding these mechanisms is vitally important for the development of novel therapies for virus induced diseases.Drosophila is a classic model organism for the study of host defense.Many important innate immune pathways,such as TOLL,IMD has been identified based on this animal model.The anti-virus mechanisms in Drosophila are highly similar to mammals.Many important anti-virus molecular pathways(such as Jak-STAT signaling pathway,etc)have been identified based on this model.The RNAi library of Drosophila makes the whole genome screening becomes possible in the level of a whole organism.Drosophila is the nature host for Drosophila C virus(DCV),which could induce fierce and typical anti-virus response once was introduced into the host Drosophila.This is the classical model for host-virus interaction mechanism research in the field.In this study,we tried to identify novel host-virus interaction mechanisms by using DCV as a challenge to infect various RNAi flies in vivo or S2 cells in vitro.ObjectiveUsing RNAi drosophila to conduct large-scale screening for DCV infection to find evolutionarily conserved virus-host interaction factors and mechanisms for providing clues for the prevention and treatment of viral infection.In addition,the discovery of non-conserved factors or mechanisms can be used as targets for arboviruses,providing new insights for the prevention and control of arboviruses.MethodRNAi flies with down-regulated expression of single gene level were used,the potential candidate genes that regulate viral infection were observed by the survival rate of drosophila infected with DCV.Then S2 cells in drosophila were immersed in double-stranded RNA to achieve specific low expression of target gene,the antiviral phenotype of candidate genes was verified in vitro.Finally,we used drosophila and S2 cells to explore the antiviral mechanism of the candidate genes.ResultWe completed the drosophila screening for DCV infection of 5895 genes,of which 531 genes regulated the survival rate of drosophila infected with DCV.Using S2 cell,we verified the anti-DCV phenotype of 21 genes.Moreover,after further research,it was found that Nipped-A gene was probably involved in host infection regulation of DCV through the Nazo branch of STING signaling pathway.ConclusionLarge-scale drosophila screening for DCV infection revealed that Nipped-A may regulate DCV infection through the STING signaling pathway.