Division of Biomedical Sciences, School of Pharmacy, the University of Nottingham Malaysia Campus, Semenyih, Selangor, Malaysia.
Faculty of Science & Technology, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia.
Pathog Glob Health. 2021 Sep;115(6):392-404. doi: 10.1080/20477724.2021.1881369. Epub 2021 Feb 1.
The proficiency of Typhi to induce cell-mediated immunity has allowed its exploitation as a live vector against the obligate intracellular protozoan . vaccine research is of great medical value due to the lack of a suitable toxoplasmosis vaccine. In the present work, we integrated antigen into a growth-dependent chromosome locus of . Typhi CVD910 strain to form recombinant . Typhi monovalent CVD910-SAG1 expressed SAG1 antigen and monovalent CVD910-GRA2 expressed GRA2 antigen. Furthermore, a low-copy stabilized recombinant plasmid encoding SAG1 antigen was transformed into CVD910-GRA2 to form bivalent CVD910-GS strain. An osmolarity-regulated promoter was also incorporated to control the gene transcription, whereas clyA export protein was included to translocate the antigen out of the cytoplasm. Both CVD910-GRA2 and CVD910-GS displayed healthy growth fitness and readily expressed the encoded antigens. When administered , CVD910-GS successfully induced both humoral and cellular immunity in the immunized BALB/c mice, and extended mice survival against virulent . In particular, the mice immunized with bivalent CVD910-GS presented the highest titers of IgG, percentages of CD4 T, CD8 T, B cells and memory T cells, and total IgG memory B cells as compared to the CVD910-GRA2 and control strains. The CVD910-GS group also generated mixed Th1/Th2 cytokine profile with secretions of IFN-ɣ, IL-2 and IL-10. This study demonstrated the importance of enhancing live vector fitness to sustain heterologous antigen expression for eliciting robust immune responses and providing effective protection against pathogen.
伤寒杆菌诱导细胞介导免疫的能力使其能够被用作针对专性细胞内原生动物的活载体疫苗。由于缺乏合适的弓形虫疫苗，疫苗研究具有重要的医学价值。在本工作中，我们将抗原整合到伤寒杆菌 CVD910 菌株的一个依赖生长的染色体基因座中，形成重组伤寒杆菌单价 CVD910-SAG1 表达 SAG1 抗原和单价 CVD910-GRA2 表达 GRA2 抗原。此外，一个低拷贝稳定的重组质粒，编码 SAG1 抗原，被转化到 CVD910-GRA2 中，形成二价 CVD910-GS 株。一个渗透压调节启动子也被整合来控制基因转录，而 clyA 外排蛋白被包含以将抗原转运出细胞质。CVD910-GRA2 和 CVD910-GS 均表现出健康的生长适应性，并能轻易地表达编码的抗原。当给予免疫时，CVD910-GS 成功地在免疫的 BALB/c 小鼠中诱导了体液和细胞免疫，并延长了小鼠对强毒力的存活。特别是，与 CVD910-GRA2 和对照菌株相比，用二价 CVD910-GS 免疫的小鼠表现出最高的 IgG 滴度、CD4 T、CD8 T、B 细胞和记忆 T 细胞的百分比，以及总 IgG 记忆 B 细胞。CVD910-GS 组还产生了混合的 Th1/Th2 细胞因子谱，分泌 IFN-ɣ、IL-2 和 IL-10。本研究证明了增强活载体适应性以维持异源抗原表达对于引发强大免疫反应和提供针对病原体的有效保护的重要性。
