13 Immunology

Abstract

The immune system of fish comprises a complex mixture of nonspecific and specific cellular and humoral responses to antigen stimulation that are similar to those of higher vertebrates. The immune system of channel catfish has received a great deal of attention with the emergence of economically important infectious diseases and the need for effective vaccines, and has provided a unique model system for study of the immune systems of lower vertebrates. Research studies have elucidated many components of the catfish immune system, although much remains unknown. Modulation of immune responses in fish in relation to water temperature is a major factor influencing the onset and duration of the immune response. Genome analysis of channel catfish using molecular approaches, such as expressed sequence tag analysis, facilitates identification of important immune response genes. A more comprehensive understanding of immune function in channel catfish is critical for the development of improved methods to manage infectious diseases in catfish aquaculture. Enhancing the immune response through vaccination, improved nutrition, or the addition of immunostimulants to the feed has been a successful strategy with other aquaculture species and will surely be explored further in channel catfish culture. The description of the catfish immune system provided here includes information derived specifically from research on channel catfish, and also includes examples from different teleost species. Where the specific functional component for channel catfish is unknown, a description of a representative teleost immune system is provided.