Study On Vibrio Alginolyticus And Harveyi Subunit Conjugate Vaccine

Outer membrane protein complex (OMPC) was extracted from V. harveyi, which was cultured in different temperature and salt concentration. Density of protein was detected with Brandford. The tested results of OMPC expressing and immunogenicity showed that: 28℃and 1mol/L NaCl is the optimal culture condition. Lipopolysaccharide (LPS) was extracted from V. alginolyticus,then LPS was conjugated to OMPC by 1-ethyl-3 (3-dimethylaminopropyl) carbodiimide (EDC) mediated condensation. During the study periods, Trachinotus cvatus were respectively immunized with the OMPC-LPS conjugates, unconjugated LPS, unconjugated OMPC, simple mixture of LPS and OMPC (all groups with DEAE adjuvant), and physiological salt solution in the same procedure. The tested results of lysozyme content showed that: no significant difference was detected among the four vaccine groups (P>0.05), but remarkable difference was observed between vaccine groups and control group (P< 0.05). As referring to the anti- EpGS021001 antibodies titer, it appeared earlier and higher in OMPC-LPS conjugates than that in unconjugated LPS and the simple mixture. And also, the anti- SpGY020601 antibodies in OMPC-LPS conjugates presented earlier with higher antibodies titer and lasted longer than that in unconjugated OMPC and the simple mixture. In addition, the protective efficiency of OMPC-LPS conjugates, unconjugated LPS, unconjugated OMPC, and simple mixture were evaluated: Challenged with EpGS021001 and SpGY020601, the RPS of OMPC-LPS conjugates group was 85% and 95% respectively, which was significantly higher than the groups of unconjugated LPS (70%) and unconjugated OMPC (75%), so did higher than that of the simple mixture (80% and 82.5%). Then Trachinotus cvatus were respectively immunized with the OMPC-LPS conjugates, conjugates with ISA763 adjuvant, conjugates with DEAE adjuvant, and physiological salt solution in the same procedure. As to the challenge test, every group was divided into four groups: the first group was challenged with EpGS021001 by injecting to abdominal cavity, the second group was dipping in EpGS021001 solution after infected with parasite, and the other two groups was respectively challenged with SpGY020601 in the above means. The protective efficiency of ISA763 adjuvant group was 90% and 70% respectively challenged with EpGS021001, which was higher than the groups of DEAE adjuvant (85% and 55%) and no adjuvant (80% and 55%) . And the RPS of ISA763 adjuvant was also higher than the other groups challenged with SpGY020601. The results showed that: this conjugates had potentiality of developing to vaccine, and ISA763 adjuvant can be used on the research of subunit vaccine of V. alginolyticus and V. harveyi.