Bacterial ghost as delivery vehicles loaded with DNA vaccine induce significant and specific immune responses in common carp against spring viremia of carp virus.

Abstract Although vaccine is a prophylaxis measure for the contagious and fatal disease caused by spring viremia of carp virus (SVCV), until now, no commercial vaccine is available for worldwide use. To find more effective and safe means for the control of SVCV infection, here, an Escherichia coli DH5α bacterial ghost (DH5α-BG, non-living bacterial) based DNA vaccine delivery system (BG/pEG-G) was constructed. Carp were injected intramuscularly by different treatments (PBS, pEGFP, BG, pEG-G and BG/pEG-G), and the immunoprotective effect induced by these treatments were analyzed. We found a stronger and longer duration immune response (serum antibody production and immune-related genes expression) can be induced in fish vaccinated with BG/pEG-G in comparison with those vaccinated with pEG-G alone. Additionally, a good immune protective effect (relative percentage survival >81.48%) was observed in fish vaccinated with BG/pEG-G vaccine at the dose of 0.2 μg DNA/g of fish. Overall, this study for the first time demonstrates the ability of DH5α-BG as DNA vaccine carrier against SVCV infection in carps, suggesting a practical multivalent strategy for the control of aquatic disease. Highlights • E.coli DH5α ghost was used as carrier to prepare a novel DNA vaccine in common carp. • Immunization with BG/pEG-G induced stronger immune response than naked pEG-G. • Immunization with BG/pEG-G enhanced disease resistance against SVCV in fish. • Bacterial ghost based DNA vaccine have prospects for application to aquatic vaccine. [ABSTRACT FROM AUTHOR]