Dengue virus (DENV) is a mosquito-borne virus that threatens approximately 2.5 billion people worldwide. Vaccines against DENV are currently unavailable. DEAD-box RNA helicases (DDXs) have been reported to participate in viral replication and host innate immune response. In the present study, we analyzed the role of 40 DDX proteins during DENV replication. Among these proteins, DDX3X showed antiviral effect against DENV infection. Viral replication significantly increased in DDX3X-silenced cells compared with the controls. The interferon (IFN)-beta transcription level decreased during the early stage of DENV infection in DDX3X-silenced cells compared with that in the controls. DDX3X could stimulate IFN-beta transcription through the IRF3 and the NF kappa B branches in DEN V-infected cells. Our data imply that DDX3X, a member of DEAD-box RNA helicase, is necessary for IFN production and could inhibit DENV replication. (C) 2014 Elsevier Inc. All rights reserved.