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Published on: July 6, 2013
[Attenuated Salmonella typhimurium as DNA delivery vehicle for DNA-mediated immunization]
Ping He1, Hong Chen, Jing-xing Liu
1Department of Microbiology, Shanghai Second Medical University, Shanghai 200025, China.
Objective:
To study whether the live attenuated AroA-auxotrophic mutant of Salmonella (S.) typhimurium (SL7207) could be used as DNA delivery vehicle to induce more efficient immune response by using the eukaryotic expression plasmid pCMV-beta as report gene.
Methods:
Murine peritoneal macrophages were infected with SL7207(pCMV-beta) in vitro, then the expression of the beta-gal were detected by X-gal staining or RT-PCR. After mice were orally immunized with SL7207(pCMV-beta), the expression of beta-gal in the lymphoid tissue were tested by RT-PCR, humoral responses were tested by ELISA, splenic lymphocyte proliferation were tested by 3H-TdR incorporation and cytotoxic T lymphocyte reaction were tested by JAM test.
Results:
The results indicated that the plasmid pCMV-beta could be delivered by SL7207 into the nucleus of the murine macrophages efficiently and expressed well in vitro; after mice received oral immunizations with attenuated S.typhimurium SL7207 harboring plasmid pCMV-beta mice, the expression of beta-gal could be detected in the spleen, mesenteric lymph nodes and Peyers patches of the mice. Furthermore, the experiments demonstrated that specific humoral immune responses and cell-mediated immune responses were successfully induced in these immunized mice. Compared with the naked DNA vaccination, SL7207 (pCMV-beta) oral immunization were more efficient in inducing cellular immune responses.
Conclusions:
Attenuated Salmonella typhimurium SL7207 could be used as DNA delivery vehicle for oral immunization, which have the ability to deliver the antigen-encoding DNA specifically to APC directly for inducing the specific immune response being dominant with cellular immune response.
