Cellular DEAD-box RNA helicase 18 (DDX18) Promotes the PRRSV Replication via Interaction with Virus nsp2 and nsp10

•The RNA helicase DDX18 interacts with the nsp2 and nsp10 of PRRSV.•DDX18 enhances the replication of PRRSV in cell culture.•Nsp2 and nsp10 relocates DDX18 from nucleus to cytoplasm.•DDX18 play a pro-viral role via its interaction with nsp2 and nsp10.

Porcine reproductive and respiratory syndrome virus (PRRSV) is an aetiological agent that can lead to reproductive failure and respiratory diseases of pigs. The replication and pathogenesis of PRRSV, although poorly understood, has been associated with the host factors. DDX18 is a member of DEAD-box RNA helicases (DDXs) family which were proved to participate in viral replication. Previously, we found the DDX18 interacts with both nsp2 and nsp10 of PRRSV by Co-Immunoprecipitation (Co-IP). In the present study, we demonstrated the interactions of DDX18 with nsp2 and nsp10, and located DDX18's binding regions as the N-terminus of nsp2 and both the N-terminus and C-terminus of nsp10. The expression of the nsp2 or nsp10 in MARC-145 cells and primary PAM cells redistributed DDX18 from the nucleus to the cytoplasm, and promoted the viral replication, but silencing of the DDX18 gene in MARC-145 cells down-regulated the replication of PRRSV. These findings proved that the cellular RNA helicase DDX18 plays a role in the replication of PRRSV, and provides insights into the understanding of PRRSV replication.