Study of a Fish Oral Vaccine Adjuvant System Based on Chitosan and Its Derivatives
Objective:The aim of this study is to optimize the preparation process,formulation,and evaluation methods for fish vaccine adjuvants derived from chitosan and its derivatives.Methods:Chitosan and its quaternary ammonium salt granule adjuvant were synthesized from chitosan of specific molecular weight and concentration through high-pressure homogenization and spray-drying techniques suitable for large-scale production.These adjuvants were loaded with inactivated Vibrio anguillarum,subsequently homogenized and emulsified with fish oil to produce an oral vaccine,which was incorporated into the feed and administered to turbot.The concentration of Vibrio anguillarum and the duration of immersion were systematically adjusted to establish an optimal immersion challenge model.Additionally,sodium alginate,β-glucan,and chitosan derivatives were combined to form a composite adjuvant.The immunoprotective efficacy of various composite adjuvants was assessed by evaluating the survival rates and the expression levels of immunity-related genes in turbot after exposure using the immersion challenge model.Results:Chitosan and chitosan quaternary ammonium salt,characterized by a molecular weight of 50 kDa and a mass concentration of 10 mg/mL,were utilized to generate homogeneous particles with a particle size of 220 nm,which served as oral vaccine adjuvants.An immersion challenge model was established for turbot where fish were exposed to Vibrio anguillarum at a concentration of 108 CFU/mL for 12 h.In the immersion challenge experiments,the composite adjuvant formulation combining chitosan quaternary ammonium salt particles and sodium alginate significantly increased the expression levels of immune-related cytokines,such as MHC-Ⅰ,by 2 to 8 times,and improved the survival rate of turbot from 0％to 30％.Conclusion:The preparation process for chitosan and its quaternary ammonium salt particle adjuvants is suitable for scale-up production.Furthermore,the composite adjuvant of chitosan quaternary ammonium salt particles and sodium alginate significantly improved the immunoprotection conferred by the oral vaccine in turbot during Vibrio anguillarum immersion challenge experiments.This research lays the foundation for the development and industrial production of an oral vaccine adjuvant system for fish based on chitosan and its derivatives.
Turbot(Scophthalmus maximus)Vibrio anguillarumChitosanOral vaccineImmersion challenge model
万方数据
维普
