The effect of chitosan oligosaccharide as an immune enhancer against Vibrio harveyi in pearl gentian grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatus )

Abstract

Chitosan oligosaccharide (COS) is an effective immunostimulant and provide some extent protection against pathogens in aquaculture. In this study, we evaluated the effects of COS on enhancing immunity of pearl gentian grouper and providing the protection against Vibrio harveyi. The results showed COS injection significantly enhanced antibody titres, the activities of catalase, lysozyme, superoxide dismutase and total serum protein. The experimental groupers were challenged with V. harveyi at 35 days post-injection, and the relative per cent survival (RPS) significantly increased in experimental groups compared with that in control group. Furthermore, the optimal immunity effect was observed with injection of COS at concentration of 8 or 10 mg/ml. The results indicated COS was an effective immune enhancer against V. harveyi by enhancing both specific and non-specific immunity in pearl gentian grouper.