Shaohong Ma's research while affiliated with Guangdong Ocean University and other places

Vibrio alginolyticus is responsible for significant economic losses in the fish industry. It is urgent to develop a vaccine against V. alginolyticus. In this study, a recombinant Lactococcus lactis expressing the VscO protein of V. alginolyticus (Lc-pMG36e-vscO) is constructed. The Lc-pMG36e-vscO has good hereditary stability. The immune responses in pearl gentian grouper (Epinephelus fuscoguttatus (♀) × E. lanceolatu (♂)) vaccinated with Lc-pMG36e-vscO are evaluated. The titers of specific antibody in the immunized grouper displayed an upward and then downward tendency during the total experiments and reached the peak value of 9.6 at the fourth week after booster immunization. The expression levels of IL-1β, IL-16, TNF-α, and MHC-1α gene in the Lc-pMG36e-vscO group were significantly upregulated after vaccination, indicating that the Lc-pMG36e-vscO could induce an effective and durable immune response. In vivo challenge of the Lc-pMG36e-vscO-immunized fish with V. alginolyticus showed a relative survival percentage of 68%. These results indicated that Lc-pMG36e-vscO could be promising as a candidate oral vaccine against V. alginolyticus.

Vaccination is one of the strategies for preventing Vibrio harveyi infection in marine-cultured animals. In this study, we prepared a formalin-killed cells of V. harveyi ZJ0603 vaccine (FKC) combined with β-glucan to immune pearl gentian grouper. The results indicated that the expression levels of IgM, TNF-α, MHC-Iα, IL-1β and IL-16 significantly increased in the spleen of the vaccinated fish. Antibody titers, activities of lysozyme and superoxide dismutase were significantly prompted in blood of the vaccinated fish. After 35 d post-vaccination, all fish were challenged intraperitoneally by virulent V. harveyi, and the relative percentage of survival (RPS) of FKC+β-glucan, FKC, β-glucan and PBS were 68 ± 5.7%, 55 ± 8.5%, 42 ± 7.5% and 32 ± 6.9%, respectively. These results demonstrated that β-glucan could be as a potential adjuvant of FKC and provide good protective effect against V. harveyi infection in the pearl gentian grouper culture.

Vibrio harveyi is the pathogen causing vibriosis in marine-cultured animals, leading to massive deaths in farmed grouper around the world. It is urgent to develop an effective vaccine to prevent vibriosis. In the previous study, we developed a V. harveyi formalin-killed cells vaccine (FKC), and sought an effective adjuvant for enhancing the immune efficacy of vaccine. In this study, we aimed to evaluate the immune responses and protective effect of FKC combined with chitosan oligosaccharide (COS) or Astragalus polysaccharides (APS) in the pearl gentian grouper♀Epinephelus fuscoguttatus × ♂E. lanceolatus. The results indicated the vaccine triggered a remarkably higher expression levels of IL-1β, IL-16, TNF-α, MHC-Iα and IgM in the kidney and spleen of groupers post-vaccination. Antibody titers, lysozyme, catalase, superoxide dismutase and total protein were significantly elevated in the vaccinated fish compared with those in the control. The experimental groupers were challenged intraperitoneally by V. harveyi at 35 d post-vaccination, and the relative percentage of survival (RPS) of group FKC + COS, FKC + APS, COS, APS and FKC were 80%, 72%, 52%, 47% and 55%, respectively. These results demonstrated COS and APS was the potential adjuvants for FKC against V. harveyi in aquaculture.