Grass carp catalase inhibits GCRV replication through ROS scavenging-mediated immune suppression and autophagy

resistance to H₂O₂ and heavy metal stress, and it inhibited GCRV replication in fish cells. Mechanistic investigations demonstrated that CiCAT suppresses GCRV replication not through activation of the host antiviral immune response, but by scavenging ROS, which attenuates host immune signaling. This reduced immune activity in turn promotes autophagy via the mTORC1/ULK1 pathway, thereby restricting GCRV replication. Collectively, our findings provide novel insights into the antiviral role of CAT in teleost fish.