Construction And Analysis Of Immune Effect Of Vibrio Harveyi Vaccines Encoding TssJ Antigen

VIbrio harveyi,a severe pathogen infects different kinds of sea animals,causes huge economic loss in aquaculture industry.At present,the main measures for the prevention and control of fish diseases are still the use of antibiotics and other drugs,but the disorderly use of antibiotics has seriously affected the aquaculture enⅥronment and the quality of aquaculture products.Because of that,it is important to take some measures to solve the problem.Recent studies have shown that the Ⅵ secretion system(T6SS)plays an important role in quorum sensing system,biomembrane formation,flagellum synthesis and cytotoxicity of VIbrio harveyi.TssJ,one of the core subunits of T6 SS,is an outer membrane lipoprotein anchored on the outer membrane by N-terminal acylated cysteine residues.Based on this,we cloned the candidate antigen TssJ from Ⅵ secretion system ofVIbrio harveyi QT520,constructed subunit vaccine and DNA vaccine,and compared their immune protective effects.In this study,Trachinotus ovatus was used as experimental animals to construct the subunit vaccine r TssJ and DNA vaccine p CTssJ.First,we analyzed the location of tssj.Western blotting and bacterial agglutination test showed that tssj was located on the cell membrane.The results of immune experiment showed that the subunit vaccine r TssJ and DNA vaccine p CTssJ could have better protective effects,and the relative immune protection efficiency was 52.39% and 69.11% respectively.The results showed that the subunit vaccine r TssJ and DNA vaccine p CTssJ could increase the actiⅥties of acid phosphatase(ACP),alkaline phosphatase(AKP),superoxide dismutase(SOD)and lysozyme(LZM).The detection of antibody level showed that both subunit vaccine r TssJ and DNA vaccine p CTssJ could effectively stimulate the body to produce antibodies,but the production of antibody of subunit vaccine r TssJ was higher than that of DNA vaccine p CTssJ.The results of immune related genes showed that,compared with the control group,immune genes such as IL10,C3,MHCIɑ and Ig M were significantly up-regulated under the immunization of subunit vaccine r TssJ and DNA vaccine p CTssJ,while TNFɑ and MX were up-regulated after the immunization of DNA vaccine p CTssJ.Compared with the subunit vaccine r TssJ,DNA vaccine p CTssJ can cause stronger up regulation of immune related genes.In conclusion,the subunit vaccine rTssJ and DNA vaccine p CTssJ can effectively improve the immune ability of Trachinotus ovatus,and have better immune protection against VIbrio harveyi QT520.This study laid a foundation for the immune control of fish.