[Efficacy of immune responses induced by anti-caries DNA vaccine-loaded bacterial ghost in mice].

OBJECTIVE: To develop an anti-caries DNA vaccine-loaded Salmonella typhimurium (St) ghost and enhance the efficacy of immune responses induced by anti-caries DNA vaccine via mucosal route. METHODS: Both pREP4 and PhiX gene E expression plasmids were transformed into StJ357 and then induced with isopropyl beta-D-1-thiogalactopyranoside (IPTG). The bacterial ghosts (BG) were collected after wash and loaded with anti-caries DNA vaccine pGJGLU/VAX. Mice were divided into four groups and immunized through the nasal route with pGJGLU/VAX-loaded BG (Group Ghost+pGJGLU/VAX), pVAX1-loaded BG (Group Ghost+pVAX1), pGJGLU/VAX-Bupivacaine complex (Group pGJGLU/VAX) and pVAX1-Bupivacaine complex (Group pVAX1), respectively. Enzyme-linked immunosorbent assay (ELISA) was used to evaluate the immune responses. RESULTS: ELISA results showed that group Ghost+pGJGLU/VAX had significantly higher level of specific anti-GLU SIgA antibody [(0.367 +/- 0.086) A/microg] compared with group Ghost+pVAX1 [(0.122 +/- 0.077) A/microg], Group pGJGLU/VAX[(0.068 +/- 0.068) A/microg] or Group pVAX1[(0.089 +/- 0.089) A/microg] (P = 0.028, 0.012 or 0.030, respectively). CONCLUSIONS: St ghost was developed successfully, which enhanced the efficacy of immune responses induced by anti-caries DNA vaccine pGJGLU/VAX via the nasal route.