Abstract：
Toxoplasma gondii is an obligate intracellular parasite that can infect a variety of mammals including humans and causes toxoplasmosis. Unfortunately, a protective and safe vaccine against toxoplasmosis hasn\'t been developed yet. In this study, we developed a DNA vaccine encoding the SRS13 protein and immunized BALB/c mice thrice with pVAX1-SRS13 through the intramuscular route (IM) or intradermally using an electroporation device (ID + EP). The immunogenicity of pVAX1-SRS13 was analyzed by ELISA, Western blot, cytokine ELISA, and flow cytometry. The protective efficacy of the pVAX1-SRS13 was investigated by challenging mice orally with T. gondii PRU strain tissue cysts. The results revealed that pVAX1-SRS13 administered through IM or ID + EP routes induced high level of anti-SRS13 IgG antibody responses (P = 0.0037 and P < 0.0001). The IFN-γ level elicited by the pVAX1-SRS13 (ID + EP) was significantly higher compared to the control group (P = 0.00159). In mice administered with pVAX1-SRS13 (ID + EP), CD8+ cells secreting IFN-γ was significantly higher compared to pVAX1-SRS13 (IM) (P = 0.0035) and the control group (P = 0.0068). Mice vaccinated with the SRS13 DNA vaccine did not induce significant IL-4 level. Moreover, a significant reduction in the number of tissue cysts and the load of T. gondii DNA was detected in brains of mice administered with pVAX1-SRS13 through ID + EP and IM routes compared to controls. In conclusion, the SRS13 DNA vaccine was found to be highly immunogenic and confers strong protection against chronic toxoplasmosis.
摘要：
弓形虫是一种专性细胞内寄生虫，可感染包括人类在内的多种哺乳动物并引起弓形虫病。不幸的是,针对弓形虫病的保护性和安全的疫苗尚未开发。在这项研究中,我们开发了编码SRS13蛋白的DNA疫苗，并使用电穿孔装置（IDEP）通过肌内途径（IM）或皮内途径用pVAX1-SRS13免疫BALB/c小鼠三次。通过ELISA分析pVAX1-SRS13的免疫原性，蛋白质印迹,细胞因子ELISA,和流式细胞术。通过用弓形虫PRU菌株组织囊肿口服攻击小鼠来研究pVAX1-SRS13的保护功效。结果显示,通过IM或ID+EP途径施用的pVAX1-SRS13诱导高水平的抗SRS13IgG抗体应答(P=0.0037和P<0.0001)。pVAX1-SRS13（IDEP）引起的IFN-γ水平明显高于对照组（P=0.00159）。在施用pVAX1-SRS13（ID+EP）的小鼠中，与pVAX1-SRS13（IM）（P=0.0035）和对照组（P=0.0068）相比，分泌IFN-γ的CD8细胞明显更高。用SRS13DNA疫苗接种的小鼠没有诱导显著的IL-4水平。此外，与对照组相比,在通过ID+EP和IM途径给药pVAX1-SRS13的小鼠的大脑中检测到组织囊肿数量和弓形虫DNA负荷的显著减少.总之,研究发现,SRS13DNA疫苗具有高度免疫原性,对慢性弓形虫病具有很强的保护作用.
