Molecular Mechanisms of the Non-Specific Immunity of Fish When Responding to Pathogen Infections

A special issue of Fishes (ISSN 2410-3888). This special issue belongs to the section "Welfare, Health and Disease".

Deadline for manuscript submissions: 30 July 2026 | Viewed by 524

Special Issue Editors

College of Fisheries, Guangdong Ocean University, Zhanjiang 524003, China
Interests: aquatic fish diseases; fish immunology; immune regulatory mechanisms
College of Animal Science and Technology, Guangxi University, Nanning 530004, China
Interests: neuroimmunity in teleost; high-throughput sequencing; evolution of the immune system

Special Issue Information

Dear Colleagues,

Diseases caused by pathogens such as viruses and bacteria remain one of the most significant challenges restricting the sustainable development of global aquaculture. Although many studies have explored the immunology and innate defense strategies of fish, the molecular mechanism of how fish defend against early infections by pathogenic bacteria through non-specific immune responses is still not clear. This Special Issue, ‘Molecular Mechanisms of the Non-specific Immunity of Fish When Responding to Pathogen Infections’, aims to highlight the interactions between pathogens, hosts, and immune regulatory mechanisms. In particular, we will focus on the latest progress in non-specific immune defense strategies. We welcome studies on the immune responses of different immune cell populations to different pathogens, the receptors and signaling pathways of immune cell populations, pathogen-derived virulence factors, and the molecular immunology of infection. By integrating research from virology, bacteriology, and fish immunology, this Special Issue aims to fill key knowledge gaps and provide a deeper understanding of the role of non-specific immunity in fish during pathogen infections. 

Dr. Yu Huang
Dr. Qi Li
Guest Editors

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Keywords

  • teleost immunity
  • immune signaling pathways
  • viral and bacterial infections
  • virulence factors

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Published Papers (1 paper)

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Research

12 pages, 586 KB  
Article
In Vitro Analysis of the Tissue Distribution, Lifespan, and Antigen-Dependent Maintenance of Specific Antibody-Secreting Cells in Nile Tilapia
by Yu Huang, Zhe Cai, Bijian Pang, Zaohe Wu, Bei Wang, Jia Cai and Jichang Jian
Fishes 2026, 11(3), 184; https://doi.org/10.3390/fishes11030184 - 19 Mar 2026
Viewed by 251
Abstract
This study aimed to elucidate the key characteristics of the humoral immune response and the tissue distribution of specific antibody-secreting cells (ASCs) in Nile tilapia (Oreochromis niloticus). A specific immune model was established by immunizing fish with human IgG. Lymphocytes were [...] Read more.
This study aimed to elucidate the key characteristics of the humoral immune response and the tissue distribution of specific antibody-secreting cells (ASCs) in Nile tilapia (Oreochromis niloticus). A specific immune model was established by immunizing fish with human IgG. Lymphocytes were isolated from the head kidney, spleen, and peripheral blood and subjected to antigen stimulation in vitro. The MTT assay, reflecting cell metabolic activity and viability, identified the optimal culture conditions as a cell concentration of 2.5 × 106 cells/mL, an antigen concentration of 2 μg/mL, and a culture duration of 72 h. Under these conditions, peripheral blood lymphocytes exhibited the most increase in metabolic activity, followed by head kidney lymphocytes, while splenic lymphocytes showed no significant response. Subsequent dynamic monitoring of antibody-secreting cells (ASCs) using ELISPOT revealed that, in the absence of antigen stimulation, ASC numbers from all three tissues declined over time. Notably, head kidney ASCs retained approximately 50% of their initial number by day 5, whereas ASCs in peripheral blood and spleen decayed to barely detectable or completely undetectable levels, respectively. These findings suggest that the head kidney may serve as a primary site for ASC persistence during the effector phase, potentially contributing to sustained humoral immunity. Although antigen stimulation did not induce significant ASC expansion, it significantly slowed their decay rate (p < 0.05), indicating an antigen-dependent maintenance role. ELISA detection of antibody levels in the culture supernatants showed a consistent trend with the ELISPOT results, further confirming the sustained functional support of antigen for ASCs. Additionally, LPS stimulation experiments demonstrated that all three tissues contained plasmablasts activatable by non-specific stimuli, with peripheral blood showing the highest proliferation fold (4–6 times). In conclusion, this study provides insights into the tissue-specific distribution, in vitro persistence, and antigen-dependent maintenance of ASCs in Nile tilapia, providing insights into the cellular basis that may contribute to humoral immune memory and laying a theoretical foundation for the rational design and application of tilapia vaccines. Full article
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