Brain immunity response of fish Eleginops maclovinus to infection with Francisella noatunensis

• Published in: Fish & shellfish immunology 2022-01, Vol.120, p.695-705
• Main Authors: Quilapi, Ana María, Vargas-Lagos, Carolina, Martínez, Danixa, Muñoz, Jose Luis, Spies, Johana, Esperguel, Ivan, Tapia, Jaime, Oyarzún-Salazar, Ricardo, Vargas-Chacoff, Luis
• Format: Article
• Language: English
• Subjects: Animals; Brain; Brain - immunology; Eleginops maclovinus; Fish Diseases - microbiology; Francisella - pathogenicity; Francisella noatunensis; Gram-Negative Bacterial Infections - veterinary; Immune response; Immunity, Innate; Iron; Perciformes - immunology; Perciformes - microbiology; Serotonin
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2021.11.026

The brain's immune system is selective and hermetic in most species, including fish, favoring immune responses mediated by soluble immunomodulatory factors such as serotonin and the availability of nutrients against infectious processes. Francisella noatunensis coexist with fish such as Eleginops maclovinus, which raises questions about the susceptibility and immune response of the brain of E. maclovinus against Francisella. In this study, we inoculated fish with different doses of Francisella and took samples for 28 days. We detected bacteria in the brain of fish injected with a high concentration of Francisella at all time points. qPCR analysis of immune genes indicated a response mainly in the medium-dose and early expression of genes involved in iron metabolism. Finally, brain serotonin levels were higher than in uninfected fish in all conditions, suggesting possible immunomodulatory participation in an infectious process. •The brain's immune system is selective and hermetic in most species, including fish.•Intracellular bacteria such as Francisella noatunensis, coexist with fish such as Eleginops maclovinus.•We detected bacteria in the brain of fish injected with a high concentration of Francisella at all time points.•The expression of immune genes indicated a response in brain-fish injected.•The expression of genes involved in iron metabolism had early response.