Construction Of TssJ Vaccine Of Vibrio Harveyi And Its Immunoprotection Effects On Epinephelus Coioides

Vibrio harveyi,one of the most common pathogens of seawater fish and invertebrates, often causing the occurrence of fish dieases, causing heavy economic losses in mariculture. Recent studies have shown that the type VI secretion system (T6SS)may play an important role in the pathogenesis of V. harveyi, such as quroum sensing,biofilm formation, flagella synthesis, and cytotoxicity. TssJ, one of the T6SS core subunits and an outer membrane lipoprotein, anchor to the outer membrane through the acylation of its N-terminal cysteine residue. In this study, we designed and constructed subunit vaccine, DNA vaccine and recombinant DNA vaccine delivered by a live pretiotics bacterial host against V harveyi and examined the protective effects of the vaccines in Epinephelus coioides.In this study, the tssJ was amplified with the genomic DNA of V. harveyi GDH11385 as template and constructed candidate vaccines, rTssJ as subunit vaccine,pCTssJ as DNA vaccine and pCTssJ/F3 as recombinant DNA vaccine delivered by a live pretiotics bacterial host. The results showed that rTssJ, pCTssJ and pCTssJ/F3 vaccinated in E. coioides model for 4 weeks and then challenged with the pathogen of V. harveyi, the relative percent survival rates (RPS) were 45%, 60%, 49.86%, respectively. The results of the level of the serum acid phosphatase activity (ACP) demonstrated that, one-week post-vaccination, both the rTssJ-vaccinated and the pCTssJ-vaccinated group were respectively highly significant that of the PBS-vaccinated control group (p <0.05),however,the pCTssJ/F3-vaccinated group was significantly higher than the PBS-vaccinated group at three weeks post-vaccination (p <0.05). At one-week post-vaccination, the level of the serum alkaline phosphatase activity (AKP) were highly significant between the pCTssJ-vaccinated group and the PBS-vaccinated control group(p <0.05), nevertheless, the levels of AKP showed that the rTssJ-vaccinated and the pCTssJ/F3-vaccinated group at two-week post-vaccination were significantly higher than the control group PBS-vaccinated, respectively. Furthermore, the AKP level of the rTssJ-vaccinated group at two- and three-week post-vaccination had high significant differences from the one-week post-vaccination,the activity level of the group reached the maximum at three-week post-vaccination. Compared to PBS-vaccinated group, the levels of the serum superoxide dismutase activity (SOD) of rTssJ-vaccinated and the pCTssJ-vaccinated group significantly increased at one-week post-vaccination(p <0.05),respectively. What's more, the significant difference of the pCTssJ/F3 vaccinated went up remarkablely, compared to that of the PBS-vaccinated control group.In conclusion, whether tssJ as a subunit vaccine, DNA vaccine, or DNA vaccine delivered by probiotic, it had an effective protection against V. harveyi challenge. The research laid a foundation for the further study of the candinate V. harveyi vaccine of strong protection rate.