Integrated Gut Microbiome and Metabolome Analysis in Largemouth Bass (Micropterus salmoides) Following Viral Infection

Largemouth bass (Micropterus salmoides) is an important aquaculture species increasingly threatened by viral diseases, particularly largemouth bass virus (LMBV), which can cause significant mortality. However, integrative analyses linking LMBV-induced gut microbiota dysbiosis to metabolomic dysfunction are limited. In this study, we profiled the intestinal microbiome and metabolome alterations in largemouth bass following LMBV infection and conducted an integrated analysis. Infected fish showed reduced alpha diversity and significant shifts in community structure, including increased relative abundances of Bacteroidota and Fusobacteriota and a decrease in Proteobacteria. Opportunistic taxa, such as Pseudomonas and Mycobacterium, were enriched after infection. Metabolomic profiling revealed differential metabolites primarily involved in amino acid and carbohydrate metabolism. Integrative correlation analyses further identified significant associations between opportunistic bacteria and putative harmful metabolites, suggesting that LMBV-induced dysbiosis disrupts host metabolic homeostasis and contributes to immune dysfunction. These findings may clarify the microbiota–metabolite landscape during LMBV infection.