The zinc-finger antiviral protein (ZAP) is a host factor that specifically inhibits the replication of certain viruses by eliminating viral mRNAs in the cytoplasm.In previous studies,we demonstrated that ZAP directly binds to the viral mRNAs and recruits the RNA exosome to degrade the target RNA.In this article,we provide evidence that a DEXH box RNA helicase,DHX30,is required for optimal antiviral activity of ZAP.Pull-down and co-immunopreci-pitation assays demonstrated that DHX30 and ZAP interacted with each other via their N terminal domains.Downregulation of DHX30 with shRNAs reduced ZAP’s antiviral activity.These data implicate that DHX30 is a cellular factor involved in the antiviral function of ZAP.