Weiss Siegfried
Molecular Immunology, GBF, German Research Centre for Biotechnology, Mascheroder Weg 1, D-38124 Braunschweig, Germany.
Int J Med Microbiol. 2003 Apr;293(1):95-106. doi: 10.1078/1438-4221-00248.
Transkingdom transfer of DNA from bacteria to other organisms, well established for bacteria, yeast and plants, was recently also extended to mammalian host cells. Attenuated intracellular bacteria or non-pathogenic bacteria equipped with adhesion and invasion properties have been demonstrated to transfer eukaryotic expression plasmids in vitro and in vivo. Here the mucosal application of attenuated Salmonella enterica spp. as DNA carrier for the induction of immune responses towards protein antigens encoded by expression plasmids, their use to complement genetic defects or deliver immunotherapeutic proteins is reviewed. Plasmid transfer has been reported for Salmonella typhimurium, S. typhi and S. choleraesuis so far but clearly other Salmonella strains should be able to transfer expression plasmids as well. Transfer of DNA is effected most likely by bacterial death within the host cell resulting from metabolic attenuation. Since these bacteria remain in the phagocytic vacuole it is unclear how the DNA from such dying bacteria is delivered to the nucleus of infected cells. Nevertheless, the efficiency that has been observed was astonishingly high, reaching close to 100% under certain conditions. Gene transfer in vivo was mainly directed towards vaccination strategies either as vaccination against infectious microorganisms or model tumors. Interestingly, in some cases tolerance against autologous antigens could be broken. In general, this type of immunization was more efficacious than either direct application of antigen, vaccination with naked DNA or using the same bacterium as a heterologous carrier expressing the antigen via a prokaryotic promoter. The ease of generating such vehicles for gene transfer combined with technology validated for mass vaccination programs and the efficacy of induction of protective immune responses makes Salmonella as carrier for mucosal DNA vaccination a highly attractive area for further research and development.
DNA从细菌向其他生物体的跨界转移在细菌、酵母和植物中已得到充分证实，最近这一现象也扩展到了哺乳动物宿主细胞。已证明减毒的胞内细菌或具有黏附及侵袭特性的非致病性细菌能够在体外和体内转移真核表达质粒。在此，我们综述了减毒肠炎沙门氏菌作为DNA载体经黏膜给药以诱导针对表达质粒所编码蛋白质抗原的免疫反应，以及其用于弥补基因缺陷或递送免疫治疗性蛋白质的相关研究。到目前为止，已报道鼠伤寒沙门氏菌、伤寒沙门氏菌和猪霍乱沙门氏菌可发生质粒转移，但显然其他沙门氏菌菌株也应能够转移表达质粒。DNA的转移很可能是由于代谢减毒导致宿主细胞内细菌死亡所引起的。由于这些细菌保留在吞噬泡中，尚不清楚来自这些濒死细菌的DNA是如何递送至受感染细胞的细胞核的。然而，观察到的效率惊人地高，在某些条件下接近100%。体内基因转移主要针对疫苗接种策略，可用于针对感染性微生物或模型肿瘤进行疫苗接种。有趣的是，在某些情况下可以打破对自身抗原的耐受性。总体而言，这种免疫方式比直接应用抗原、裸DNA疫苗接种或使用同一细菌作为通过原核启动子表达抗原的异源载体更为有效。这种用于基因转移的载体易于构建，结合了经大规模疫苗接种计划验证的技术以及诱导保护性免疫反应的功效，使得沙门氏菌作为黏膜DNA疫苗的载体成为一个极具吸引力的进一步研究和开发领域。
