Immunological Function in Teleost Fish

Teleost fish possess a sophisticated immune system that integrates innate and adaptive mechanisms to detect, respond to and eliminate pathogens in diverse aquatic environments. Innate defences include physical barriers at skin and mucosal surfaces, phagocytic cells, the complement cascade and acute-phase proteins, which provide rapid, non-specific protection. Adaptive responses are mediated by B and T lymphocytes, producing immunoglobulins and cytokines that confer antigen-specific immunity and immunological memory. Unique to teleosts are lineage-specific expansions of immune gene families resulting from whole-genome duplications, which underpin novel acute-phase reactants and diversified antibody isotypes. Mucosal tissues such as the gastrointestinal tract, gills and skin form major sites of antigen encounter, with gut-associated lymphoid tissue communicating with the liver via bile to coordinate homeostatic and inflammatory responses. Insights into teleost immunobiology have direct application to aquaculture health management, vaccine development and environmental monitoring, and contribute to comparative understanding of vertebrate immunity.

Research from Nature Portfolio

Integrative transcriptomic and proteomic analysis of tilapia gut and liver tissues has revealed distinct immune specialisations in each organ. In healthy fish, the gut exhibits a broader repertoire of adaptive immune transcripts, whereas the liver is enriched in innate components. Upon bacterial challenge, differential changes in both gut and liver gene expression diminish, indicating coordinated modulation of barrier and systemic defences. Proteins isolated from bile and intestinal mucus suggest that the liver supplies immune effectors to the gut during inflammation, highlighting a conserved gut-liver immunological axis.

In a model of bacterial infection, tilapia inoculated with a common aquaculture pathogen exhibited rapid modulation of acute-phase proteins in serum. Positive acute-phase reactants such as haptoglobin, ceruloplasmin and complement C3 increased within hours, while negative reactants declined. This protein dynamics paralleled leukocyte infiltration and reactive oxygen species production, demonstrating that fish mirror mammalian inflammatory kinetics and validating tilapia as an experimental system for host-pathogen studies.

Immunological Function in Teleost Fish publication trend

The graph below shows the total number of articles in immunological function in teleost fish across all publications each year (not limited to Nature Index journals).

Technical terms

Teleost: A diverse infraclass of bony fish encompassing the majority of modern species.

Innate immunity: The evolutionarily ancient, non-specific defence system providing immediate protection.

Adaptive immunity: The antigen-specific arm of immunity involving lymphocytes and memory formation.

Acute-phase protein: A plasma protein whose concentration fluctuates in response to inflammation.

Cytokine: A signalling molecule secreted by immune cells to orchestrate responses.

Complement system: A cascade of plasma proteins that enhance pathogen clearance and inflammation.

References

1. Fish gut-liver immunity during homeostasis or inflammation revealed by integrative transcriptome and proteome studies. Scientific Reports (2016).
2. Acute-phase proteins during inflammatory reaction by bacterial infection: Fish-model. Scientific Reports (2019).
3. Expression and Immune Response Profiles in Nile Tilapia (Oreochromis niloticus) and European Sea Bass (Dicentrarchus labrax) During Pathogen Challenge and Infection. International Journal of Molecular Sciences (2024).
4. Catch of the Day: New Serum Amyloid A (SAA) Antibody Is a Valuable Tool to Study Fish Health in Salmonids. Cells (2023).
5. High-throughput proteomic profiling of the fish liver following bacterial infection. BMC Genomics (2018).