Molecular Innate Immunity in Teleost Fish: Review and Future Perspectives

Innate immune response is a primitive form of defense mechanism existent in plants and animals. It is a complex system which, in vertebrates, is composed of cellular and humoral responses. The vertebrate teleost fish, which diverged from the tetrapod lineage about 450 million years ago, has an innate immune component that shows considerable conservation with higher vertebrates particularly in mammals highlighted by the presence of orthologous pattern recognition receptors (PRRs) and stimulated cytokines. However, there is also increasing evidence of teleost fish components and functions that are not observed in mammals suggesting complexity and diversity in teleost fish innate immune function. Knowledge about the network and function of these innate immune-related molecules in model and/or economically important fish is therefore important and new molecular biological tools such as large scale gene expression profiling including DNA microarrays and protein-based techniques will help elucidate such information. This review focuses on the molecular innate immune mechanisms in teleost fish in reference to the known mammalian system. It also includes future perspectives on how this basic knowledge coupled with existing molecular biological techniques can contribute to the control of fish disease and thereby improve aquaculture.