School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, UK.
Vaccine. 2010 Nov 3;28(47):7523-8. doi: 10.1016/j.vaccine.2010.09.001. Epub 2010 Sep 17.
Attenuated Salmonella enterica offers a vaccine delivery route that has the benefits of enhanced immunogenicity and oral delivery. The majority of immunization studies have been conducted to deliver recombinant proteins, expressed from a gene that is either chromosomally integrated or carried on a low- or medium-copy number plasmid. There are, however, an increasing number of reports demonstrating the delivery of DNA vaccines, but the high-copy number plasmids that are preferentially used for this application are unstable in Salmonella. Here, we use the Operator-Repressor Titration (ORT) plasmid maintenance system in Salmonella enterica serovar Typhimurium to deliver a high-copy number plasmid expressing the Mycobacterium tuberculosis gene mpt64 to mice. MPT64 expression was detected in phagocytes using immunofluorescence microscopy following Salmonella-mediated delivery of the DNA vaccine. The indicative CD8+ responses measured by antigen-specific IFN-γ were higher from the live bacterial vector than from injected plasmid DNA, and a reduction in the pulmonary bacterial load was seen following an aerogenic challenge. This illustrates the potential of live attenuated Salmonella as oral tuberculosis vaccine vectors.
减毒鼠伤寒沙门氏菌提供了一种疫苗传递途径，具有增强的免疫原性和口服传递的优点。大多数免疫研究都是为了递送重组蛋白而进行的，这些蛋白是由染色体整合或低拷贝数或中等拷贝数质粒携带的基因表达的。然而，越来越多的报告表明可以传递 DNA 疫苗，但是在这种应用中首选的高拷贝数质粒在沙门氏菌中不稳定。在这里，我们使用鼠伤寒沙门氏菌血清型 Typhimurium中的 Operator-Repressor Titration（ORT）质粒维持系统来递增高拷贝数质粒，该质粒表达结核分枝杆菌基因 mpt64 给小鼠。在用沙门氏菌介导的 DNA 疫苗传递后，使用免疫荧光显微镜检测吞噬细胞中的 MPT64 表达。通过抗原特异性 IFN-γ 测量的指示性 CD8+反应从活细菌载体比从注射的质粒 DNA更高，并且在气溶胶挑战后观察到肺部细菌负荷减少。这说明了减毒活沙门氏菌作为口服结核病疫苗载体的潜力。
