Low endotoxic and immunogenic outer membrane vesicle vaccine platform derived from an MsbB-deficient Salmonella enteritidis mutant = MsbB 결핍 살모넬라 티피뮤리움 유래 저독성 및 면역원성 세균외막소포백신 플랫폼 개발

Abstract

A low endotoxic Outer membrane vesicles (OMVs) vaccine platform was established with an msbB genedeleted (ΔmsbB) Salmonella enteritidis mutant. The Salmonella ΔmsbB mutant displayed lipopolysaccharide phenotypic changes showing faster migration of the lipid A-core region in an SDS-PAGE analysis and the increased amount of penta-acyl lipid A due to the MsbB deficiency. In an endotoxicity assay, BALB/c mice injected intraperitoneally with the Salmonella ΔmsbB mutant survived for 10 days, whereas mice injected intraperitoneally with the wild type survived for 5 days. Also, all mice inoculated orally with the ΔmsbB mutant survived for 30 days but 70% of mice inoculated orally with wild type survived. Electron microscopically, the Salmonella ΔmsbB mutant produced a larger amount of OMVs than the wild type. In immunogenicity tests, all sera from mice groups immunized with the wild type, ΔmsbB mutant, and their OMVs, showed significantly higher IgG levels. This result was consistent with higher bactericidal activities against wild type S. enteritidis, compared to the negative control. However, there were no significant differences in serum IgG levels and the bactericidal activities of the immune sera between the four mice groups. The viable counts of S. enteritidis recovered from the spleen and liver of four preimmunized mice groups after 5 days of the bacterial challenge showed significant reductions of the live bacteria. Conclusively, the ΔmsbB mutant of S. enteritidis produced relatively low endotoxic OMVs, which was verified in this study for its potential to be a non-replicating Salmonella vaccine candidate.