From immunology to protection – immunology of vaccination in aquaculture species

Aquaculture faces mounting disease challenges due to high-density farming and environmental stressors, driving the need for effective fish vaccination strategies. This chapter provides a comprehensive overview of teleost immunology in the context of disease prevention, spanning innate and adaptive responses, mucosal versus systemic immunity, and the generation of immunological memory. We discuss the cellular and molecular underpinnings of host–pathogen interactions, including the roles of phagocytes, cytokines, B and T lymphocytes, and immunoglobulin isotypes (IgM, IgD, IgT). The mechanisms of vaccine-induced protection are examined across delivery routes (injection, immersion, oral) and vaccine platforms (inactivated, live attenuated, subunit, DNA, RNA). Case studies highlight discrepancies between laboratory and field efficacy, emphasizing the influence of environmental variables and host genetics. Finally, we explore emerging technologies – including nanoparticle-based delivery, immunoinformatics-guided design, and thermostable formulations – that are reshaping the future of fish vaccines. This chapter aims to bridge foundational fish immunology with practical vaccinology, offering a mechanistic and applied framework to support sustainable aquaculture.