Transcriptome analysis reveals the response mechanism of largemouth bass (Micropterus salmoides) brain to MSRV...

Micropterus salmoides is an economically significant freshwater fish that faces serious threats from various pathogens. Micropterus salmoides rhabdovirus (MSRV) is a pathogenic virus that primarily infects juvenile fish, leading to severe disease. Although some studies have reported the transcriptome sequencing of immune-related tissues in Micropterus salmoides after MSRV infection, studies focusing on the central nervous system remain scarce. In this study, largemouth bass juvenile fish were infected by intraperitoneal injection of MSRV. Severe external clinical sign, together with high virus load were detected in brain tissues after MSRV infection. Transcriptomic analysis showed that the expression level of 658 genes (297 up-regulated genes and 361 down-regulated) in brain tissues was significantly altered. First, KEGG analysis indicated that differentially expressed genes (DEGs) were positively enriched in the pathways related to immune signaling and cell death, such as JAK-STAT signaling pathway, cytokine-cytokine receptor interaction and apoptosis. Next, Most DEGs within the significant enrichment of "Citrate cycle", "Oxidative phosphorylation", "proteasome" and "ribosome" were downregulated in brain tissues infected with MSRV. Additionally, we found that MSRV infection reduces both the mitochondrial membrane potential and ATP production in largemouth bass brain tissues, thereby inhibiting viral replication. Altogether, this study revealed immune-related genes and pathways that defend against MSRV infection, as well as other cellular processes potentially involved in host antiviral responses or viral invasion. These findings are pending functional validation. All these results provided a reference for further in-depth study mechanisms of viral-host interactions in teleost fish.