Review
Although fish immunology has progressed in the last few years, the contribution of the normal endogenous microbiota to the overall health status has been so far underestimated. In this context, the establishment of a normal or protective microbiota constitutes a key component to maintain good health, through
competitive exclusion mechanisms, and has implications for the development and maturation of the immune system. The normal microbiota influences the innate immune system, which is of vital importance for the disease resistance of
fish and is divided into physical barriers, humoral and cellular components. Innate humoral parameters include antimicrobial peptides, lysozyme, complement components, transferrin, pentraxins, lectins, antiproteases and natural antibodies, whereas nonspecific cytotoxic cells and phagocytes (monocytes/macrophages and
neutrophils) constitute innate cellular immune effectors. Cytokines are an integral
component of the adaptive and innate immune response, particularly IL-1b, interferon, tumor necrosis factor-a, transforming growth factor-b and several chemokines regulate innate immunity. This review covers the innate immune mechanisms of protection against pathogens, in relation with the installation and composition of the normal endogenous microbiota in fish and its role on health. Knowledge of such interaction may offer novel and useful means designing
adequate therapeutic strategies for disease prevention and treatment.
Peer reviewed