Comprehensive Study of Immune Genes and Antibody Diversity in Atlantic Cod

Greg Howard
4th July, 2024

Comprehensive Study of Immune Genes and Antibody Diversity in Atlantic Cod

Image Source: Natural Science News, 2024

Key Findings

  • The study by the University of Oslo focused on the immune system of the Atlantic cod, which lacks the typical MHCII pathway crucial for T cell-dependent antibody responses
  • Despite this deficiency, the Atlantic cod has evolved unique mechanisms to mount an effective immune response, including a diverse antibody repertoire
  • The findings provide insights into the adaptability and evolution of vertebrate immune systems, potentially informing new strategies for disease management in other species, including humans
The Atlantic cod is a notable species in the Atlantic Ocean, known for its substantial population despite having an unusual immune system. Researchers at the University of Oslo have conducted a study to understand the molecular details of the Atlantic cod's immune response, particularly focusing on its immunoglobulin loci and antibody repertoire[1]. This study addresses a significant puzzle in vertebrate immunology, as the Atlantic cod lacks the Major Histocompatibility Complex class II (MHCII) antigen presentation pathway, which is typically essential for T cell-dependent antibody responses. The immune system of vertebrates, including mammals, is complex and typically involves various molecules and mechanisms that have evolved over millions of years. For instance, the adaptive immune system (AIS) in mammals, which relies on lymphocytes and antigen receptors generated by somatic recombination, emerged around 500 million years ago in jawed fish[2]. This system is intricate and includes many elements absent in jawless vertebrates. However, jawless fish have developed a similar non-RAG-based AIS through convergent evolution, highlighting the diverse evolutionary paths immune systems can take. In the context of skin immunity, teleost fish, which are ancient bony vertebrates, possess a skin-associated lymphoid tissue (SALT) that plays a crucial role in maintaining skin homeostasis[3]. Teleost SALT is structurally similar to gut-associated lymphoid tissue and contains a diverse microbiota. This similarity suggests that evolutionary selective forces have shaped analogous B-cell responses in these tissues. Specifically, the immunoglobulin IgT, specialized in gut immunity, is also predominant in skin mucosal immunity in teleosts, indicating a conserved principle across different mucosal surfaces. Interestingly, earlier studies have shown that IgD, an immunoglobulin previously thought to be exclusive to primates and rodents, is also present in teleost fish like the channel catfish[4]. This finding suggests that IgD is an ancient immunoglobulin that existed in vertebrates ancestral to both mammals and ray-finned fishes, and it may have played a crucial role in the early evolution of the immune system. The study by the University of Oslo delves into the unique immune characteristics of the Atlantic cod, particularly its lack of the MHCII pathway. This pathway is critical for T cell-dependent antibody responses in most vertebrates, making the Atlantic cod's immune response particularly intriguing. By characterizing the immunoglobulin loci and analyzing the antibody repertoire, researchers aim to uncover how the Atlantic cod mounts an effective immune response despite this apparent deficiency. The findings from this study could provide new insights into the adaptability and evolution of immune systems in vertebrates. Understanding the molecular basis of the Atlantic cod's immune response could reveal alternative mechanisms of immune defense that have allowed this species to thrive in its environment. Additionally, these insights could have broader implications for immunology, potentially informing the development of new strategies for managing diseases in other species, including humans. In summary, the research conducted by the University of Oslo on the Atlantic cod's immune system sheds light on the diversity and adaptability of vertebrate immune responses. By examining the immunoglobulin loci and antibody repertoire, this study contributes to our understanding of how different species have evolved unique mechanisms to maintain effective immune defenses, even in the absence of conventional pathways like MHCII.

BiotechGeneticsMarine Biology

References

Main Study

1) Systematic characterization of immunoglobulin loci and deep sequencing of the expressed repertoire in the Atlantic cod (Gadus morhua)

Published 3rd July, 2024

https://doi.org/10.1186/s12864-024-10571-0

Related Studies

2) Origin and evolution of the adaptive immune system: genetic events and selective pressures.

https://doi.org/10.1038/nrg2703

3) Teleost skin, an ancient mucosal surface that elicits gut-like immune responses.

https://doi.org/10.1073/pnas.1304319110

4) A novel chimeric Ig heavy chain from a teleost fish shares similarities to IgD.

Journal: Proceedings of the National Academy of Sciences of the United States of America, Issue: Vol 94, Issue 9, Apr 1997


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