Grass Carp Reovirus triggers autophagy enhancing virus replication via the Akt/mTOR pathway

Autophagy impacts the replication cycle of many viruses. Grass Carp Reovirus (GCRV) is an agent that seriously affects the development of the grass carp aquaculture industry. The role of autophagy in GCRV infection is not clearly understood. In this study, we identified that GCRV infection triggered autophagy in CIK cells, which was demonstrated by transmission electron microscopy, the conversion of LC3B I to LC3B II and the level of autophagy substrate p62. Furthermore, we found that GCRV infection activated Akt-mTOR signaling pathway, and the conversion of LC3B I to LC3B II was increased by inhibiting mTOR with rapamycin (Rap) but decreased by activating Akt with insulin. We then assessed the effects of autophagy on GCRV replication. We found that inducing autophagy with Rap promoted GCRV proliferation but inhibiting autophagy with 3 MA or CQ inhibited GCRV replication in CIK cells. Moreover, it was found that enhancing Akt-mTOR activity by insulin, GCRV VP7 protein and viral titers of GCRV were decreased. Collectively, these results indicated that GCRV infection induced autophagy involved in GCRV replication via the Akt-mTOR signal pathway. Thus, new insights into GCRV pathogenesis and antiviral treatment strategies are provided.