Characterization of Immune Response Against <i>Mycobacterium marinum</i> Infection in Coho Salmon (<i>Oncorhynchus kisutch</i>)
<i>Mycobacterium marinum</i> is an opportunistic pathogen prevalent in aquatic environments, causing significant morbidity in fish, including Coho salmon (<i>Oncorhynchus kisutch</i>), a species increasingly cultured in Chinese salmonid aquaculture. This study investigated th...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
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| Series: | Fishes |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2410-3888/10/6/268 |
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| Summary: | <i>Mycobacterium marinum</i> is an opportunistic pathogen prevalent in aquatic environments, causing significant morbidity in fish, including Coho salmon (<i>Oncorhynchus kisutch</i>), a species increasingly cultured in Chinese salmonid aquaculture. This study investigated the immune response of Coho salmon to <i>M. marinum</i> infection and the bacterial proliferation dynamics in the liver and kidney. Transcriptome analysis revealed 5028 differentially expressed genes (DEGs) in the kidney and 3419 DEGs in the liver at 6 weeks post-infection. Gene Ontology and KEGG enrichment analysis highlighted pathways such as cytokine–cytokine receptor interaction, metabolic pathways, and Toll-like receptor signaling in the kidney, while the DEGs in the liver were enriched in metabolic pathways, immune system processes, and stress and defense responses. The temporal expression profiling of 15 immune-related genes, including acute-phase proteins (serum amyloid A-5 and hepcidin), cytokines (TNF-α, IL-1β, IL-17A), chemokines (CXCL13 and CCL19), pattern recognition receptors (Toll-like receptor 13), and other immune-related genes, showed significant upregulation against <i>M. marinum</i> infection, with stronger responses in the liver. Furthermore, it was found that there was a progressive proliferation of <i>M. marinum</i> in the infected liver and kidney from approximately 2.5 log<sub>10</sub> cfu/g at week 2 to about 6 log<sub>10</sub> cfu/g by 6 weeks, with a significantly higher load in the liver. These findings provide critical insights into the immune mechanisms of Coho salmon against <i>M. marinum</i> and the pathogen’s tissue-specific proliferation, offering a foundation for developing targeted control strategies against <i>M. marinum</i> in aquaculture. |
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| ISSN: | 2410-3888 |