EcSnx27 facilitates in vitro release of Singapore grouper iridovirus and interacts with its major capsid protein.

Sorting nexin 27 (Snx27), a member of the sorting nexin (SNX) family, plays crucial roles in cell signaling, organelle motility, protein sorting and membrane remodeling/trafficking. While existing studies have focused on the functions of SNXs in mammalian viral diseases and immune regulation, little is known about fish-encoded SNXs, particularly their regulatory roles in aquatic virus infection. In this study, we characterized the Snx27 from the orange-spotted grouper (Epinephelus coioides) and found that it facilitates the in vitro release of Singapore grouper iridovirus (SGIV), as evidenced by the detection of viable virions in the culture supernatants of SGIV-infected grouper spleen (GS) cells. Notably, EcSnx27 had no impact on SGIV replication. Furthermore, IP-MS data revealed an interaction between EcSnx27 and the major capsid protein (MCP) of SGIV, which was further validated using Co-IP, molecular docking and yeast two-hybrid assays. These results suggest that the increased number of viral particles in the supernatant may be mediated by the Snx27-related pathway. Overall, our study demonstrates that EcSnx27 promotes viral release and interacts with SGIV-MCP. These findings significantly advance to our understanding of the roles of fish SNXs in the innate immune response and the process of viral release during iridovirus infection.