Development Of An Oral Inactivated Vaccine For Vibrio Anguillarum Based On Chitosan And Aluminum Adjuvant

Vibrio anguillarum is a common marine pathogen in mariculture industry.Under the general trend of intensive farming and artificial farming,the periodic outbreak of Vibriosis has hindered the development of aquaculture in our country and the world.Vaccination is an effective means to prevent and treat pathogen.However,most of the current commercial vaccines are injection vaccines with compound adjuvants,and there are relatively few research reports on immersion and oral vaccines.Taking into account factors such as safety,practical operability,and protective effects,we believe that oral administration of inactivated vaccines with adjuvants or immunestimulators can combine the advantages of oral immunization with the characteristics of adjuvants,which is of significance as a research direction.However,oral vaccines have some pain points yet to be solved,such as antigen degradation and poor protection.This project developed an oral inactivated vaccine of Vibrio anguillarum based on chitosan and aluminum adjuvant,established immunity and challenge model in vivo,and finally investigated the immune effect together with the immune protection of the adjuvant.The experimental group has a significantly higher relative immune protection rate than the control group,reaching 47.4%,indicating the adjuvant played a role in oral delivery procedure and stimulated immune response after then.The immune response signal pathways and related cytokines stimulated were specifically studied by means of ELISA,RT-PCR,Western-Blot and flow fluorescence analysis.In the experimental group,the expression levels of genes such as IL-6,IL-12,IFN-y and IgM were up-regulated during the immunization period,indicating that both Thl and Th2 cellular immune responses were stimulated.In addition,the ratio of IgT+/IgM+ B cells in the intestine was increased,and IgM antibody expression is detected in the serum,indicating the adjuvant induced local and systemic immune responses.In summary,this project explored the application potential of chitosan and aluminum salt as an oral vaccine adjuvant,and provided a reference for the subsequent development of turbot oral vaccine.