Grass Carp Reovirus (GCRV) infection activates the PERK-eIF2α pathway to promote the viral replication.

Grass carp reovirus (GCRV) belongs to the genus Aquareovirus and is responsible for causing serious hemorrhagic disease in grass carp (Ctenopharyngodon idella), characterized by high mortality rates. Numerous animal viruses have been shown to activate endoplasmic reticulum stress (ERS). However, the potential for GCRV infection to induce ERS and its implications for viral infection remain unclear. In this study, we demonstrated that GCRV infection induces ERS, activates the protein kinase R-like ER kinase (PERK) pathway, and inhibits both the inositol-requiring enzyme 1 (IRE1) and activating transcription factor 6 (ATF6) pathways within the unfolded protein response (UPR). Additionally, we modulated the levels of ERS and UPR pathways in CIK cells through drug treatment and small interfering RNAs (siRNAs). Our findings revealed that the onset of ERS accelerated GCRV infection, while the ATF6 and IRE1 pathways within the UPR negatively regulated GCRV infection. Conversely, the PERK pathway facilitated GCRV infection. Furthermore, we showed that GCRV infection induced oxidative stress, with the production of reactive oxygen species (ROS) being positively regulated by the PERK pathway and the downstream gene endoplasmic reticulum oxidoreductase-1α (ERO1α). Notably, ROS promoted GCRV infection. Collectively, our findings indicate that GCRV infection activates ERS, which in turn promotes viral infection through the PERK-ERO1α-ROS signaling pathway. Thus, the PERK pathway may serve as a novel antiviral target for the prevention of GCRV infection.