Modulation of Nonspecific Defence Mechanisms and Protection Against Diseases in Fish

Abstract

Siwicki, A. K., M. Morand, P. Klein, M. Studnicka. E. Terech-~!ajewska: Modulation of Non-specific Defence Mechanisms and Protection against Diseases ill Fish. Acta vet. Emo, 1998,67: 323-328.The use of immunomodulators in fish culture offers a wide range of attractive methods for inducing or modulating protection against diseases. Several promising synthetic drugs and biological response modifiers stimulate or modulate the nonspecific defence mechanisms and specific cellular and humoral immune responses in fish. This article reviews the literature on the influence of biostimulants on the cellular and humoral defence mechanisms in fish, and present the possibility to application of immunostimulants for control of infectious diseases in aquaculture. Fish, immllflostimuiallts, defence mechanismsProtection of fish against bacterial diseases by specific vaccines has been an important method for many years in aquaculture. However, defence mechanisms in the lower vertebrates are somewhat different from those in mammals, and some immunization techniques when actually applied to hatchery conditions are not as effective as they should be. Therefore, research is concentrating on how to improve the potency and efficacy of the antigens and how to optimally activate the nonspecific defence mechanisms and specific cellular and humoral immune responses. When a fish initially encounters a pathogen, the nonspecific defence mechanisms are more important than the specific immune response, as the latter requires a long time for antibody build-up and specific cellular activation. In general, fish have short life spans and most live in cool water environments which slows development of the specific immune response. Nonspecific defence barriers and mechanismsThe nonspecific defence barriers already in place include physical epithelial shield of the scales, skin and the mucus. If an infectious agent is entrapped by the mucopolysaccharide complexes of the mucus, it may be scuffed from the fish or held to be digested by the mucus lytic enzymes. In most cases, the pathogenic microorganisms are destroyed by digestive and lytic enzymes. Inflammation may result at a tissue-damaged site, resulting in the migration of leukocytes to wound areas and the elevation of serum component concentrations, including C-reactive protein, transferrin, lysozyme, ceruloplasmine and complement components.

Influence of feeding the leucine metaboliteβ-hydroxy-β-methylbutyrate (HMB) on the non-specific cellular and humoral defence mechanisms of rainbow trout (Oncorhynchus mykiss)

“…The results showed that HMB in the diet increased the phagocytes and lymphocytes T and B activities, lysozyme activity in plasma, and total Ig levels in the serum of rainbow trout. Similar immunostimulatory effects of other natural products such as glucans, chitosan, heat extract from Watasenia scintillans and dimer lysozyme (KLP ‐602) on the in vitro and in vivo function of macrophages and lymphocytes have also been observed in fish (Robertsen et al, 1990; Siwicki and Anderson, 1993; Siwicki et al, 1996, 1998; Morand et al, 1999). Several previous in vitro and in vivo studies with HMB in animals strongly suggest that HMB affects the macrophage and lymphocyte functions, enhancing the animal's ability to fight disease effectively and resist infection (Nonnecke et al, 1991; Fuller and Nissen, 1994; Nissen et al, 1994; Gatnau et al., 1995; Ostaszewski et al, 1998).…”

Innate immunity of fish (overview)

“…Some comprehensive reviews have been published recently covering the many immunostimulants tested in aquaculture. Their mode of action and application has been described, as well as their enhancement of innate and acquired immune parameters and effects on survival and disease resistance [152,170,171]. In theory the immunostimulation of innate immune parameters using chemicals that stimulate the PRR of fish looks promising.…”

Effect of two medicinal herbs (Astragalus radixandLonicera japonica) on the growth performance and body composition of juvenile pikeperch [Sander lucioperca(L.)]

“…The potential importance of non‐specific immunoprophylactics with the application of immunostimulators that activate non‐specific defence mechanisms and improve the resistance of fish to disease seems to be more significant than immunizations (e.g. Anderson 1992; Siwicki, Anderson & Rumsey 1994; Siwicki, Morand, Klein, Studnicka & Terech‐Majewska 1998; Siwicki, Zakęś, Fuller, Nissen, Trapkowska, Głąbski, Kowalska, Kazuń & Terech‐Majewska 2006). One advantage of immunostimulators is that they can be delivered to the fish with their feed as so‐called interventional granules.…”