Recent developments in fish immunostimulants

Abstract

Immunostimulants in aquaculture has created lot of interest as a suitable prophylaxis agent to control fish diseases. The efficacies of immunostimulants such as glucan and lactoferrin have been well studied in fish. Recently, new immunostimulants, like the nucleotides and CpG motif of DNA have been reported. Usually, immunostimulants can increase the activities of phagocytic cells such as phagocytosis, NBT and chemotaxis. Several immunostimulants also stimulate the natural killer cells, complement, lysozyme and antibody responses of fish. Immunostimulants activate several cytokines such as interleukin 1β and CC chemokines. The activation of these immunological functions is associated with increased protection against infectious diseases. For an effective use of immunostimulants, the timing, dosage, mode of administration and the physiological condition of fish need to be taken into consideration.