The Role of Gut Microbiota in Fish Viral Infection: Mechanisms and Microbiota-Targeted Interventions

Viral diseases represent one of the major threats to the global aquaculture industry. In recent years, the relationship between gut microbiota and viral infections in fish has garnered increasing attention. The gut microbiota contributes critically to fish health and is involved in antiviral defense through immune regulation, secretion of microbial metabolites, as well as enhancement of barrier function. The gut microbiota, host immunity, and viral infection form a complex and dynamic interaction network. A substantial body of 16S rRNA and metabolomics correlation studies has indicated that viral infections can alter the gut microbiota in fish, while changes in the gut microbiota can, in turn, influence viral infection. In this review, we summarize the regulatory effects of gut microbiota on fish viral infections, explore the interactions between the gut microbiota, immune system, and viral pathogenesis, and discuss future research directions and potential application prospects. By outlining the three-dimensional interaction network of "microbiota-immune-virus" in fish, this review not only lays a theoretical foundation for developing targeted microecological strategies for green disease control but also provides an evolutionary perspective for understanding host-microbe coevolution in vertebrates.