Fish microsporidia: immune response, immunomodulation and vaccination

Area of Science:

• * Veterinary immunology and parasitology.
• * Fish health and disease resistance.

Background:

• * The immune response of fish to microsporidia, a significant parasitic threat, remains largely uncharacterized.
• * Current research aims to elucidate the complex immune events involved in combating these infections.

Purpose of the Study:

• * To review the primary resistance mechanisms against fish microsporidia.
• * To discuss the roles of innate and adaptive immunity, immunomodulation, and vaccination strategies.

Main Methods:

• * Review of existing literature on fish microsporidiosis and immune responses.
• * Analysis of ultrastructural studies on inflammatory cells and molecules.
• * Examination of research on humoral and cellular adaptive immunity, immunomodulators (glucans), and vaccine development.

Main Results:

• * Innate immunity involves inflammatory cells (macrophages, neutrophils) and molecules (MHC).
• * Adaptive immunity's role is complex: antibody responses vary in protection, and cellular immunity is understudied.
• * Glucans show potential for immunomodulation, enhancing non-specific immune responses.

Conclusions:

• * Understanding fish immune responses is crucial for controlling microsporidiosis.
• * Vaccination holds promise, with a recent spore-based vaccine demonstrating efficacy against microsporidial gill disease in salmon.
• * Further research into cellular immunity and novel vaccine strategies is warranted.