Cyprinid herpesvirus 3 ORF24 facilitates viral replication via RLR signaling pathway-mediated innate immune evasion

Cyprinid herpesvirus 3 (CyHV-3) poses a significant threat to common carp aquaculture, yet the mechanisms underlying its immune evasion remain poorly understood. In this study, we identify the viral protein ORF24 as a critical antagonist of the RLR-mediated innate immune response. Our findings demonstrate that ORF24 significantly suppresses the expression of type I interferon and downstream antiviral genes, thereby facilitating viral replication. Mechanistically, ORF24 directly interacts with key signaling molecules, including MITA, TBK1, IRF3, and IRF7, without affecting their steady-state protein levels. Furthermore, ORF24 disrupts the recruitment of IRF3 and IRF7 by MITA and TBK1 in a dose-dependent manner, effectively blocking the activation of interferon signaling downstream of the RLR pathway. Collectively, this study elucidates a novel mechanism by which CyHV-3 ORF24 subverts host innate immunity to achieve immune evasion, establishing ORF24 as a potential target for the development of therapeutic interventions against CyHV-3 infection.