Department of Parasitology, Shandong University School of Medicine, Jinan, Shandong Province, People's Republic of China.
Parasit Vectors. 2013 Jun 14;6:175. doi: 10.1186/1756-3305-6-175.
Toxoplasma gondii is an obligate intracellular parasite that can pose a serious threat to human health by causing toxoplasmosis. There are no drugs that target the chronic cyst stage of this infection; therefore, development of an effective vaccine would be an important advance. Aspartic proteases play essential roles in the T. gondii lifecycle. The parasite has four aspartic protease encoding genes, which are called toxomepsin 1, 2, 3 and 5 (TgASP1, 2, 3 and 5, respectively).
Bioinformatics approaches have enabled us to identify several promising linear-B cell epitopes and potential Th-cell epitopes on TgASP1, thus supporting its potential as a DNA vaccine against toxoplasmosis. We expressed TgASP1 in Escherichia coli and used the purified protein to immunize BALB/c mice. The antibodies obtained were used to determine where TgASP1 was localized in the parasite. We also made a TgASP1 DNA vaccine construct and evaluated it for the level of protection conferred to mice against infection with the virulent RH strain of T. gondii.
TgASP1 appears to be a membrane protein located primarily at the tip of the T. gondii tachyzoite. Investigation of its potential as a DNA vaccine showed that it elicited strong humoral and cellular immune responses in mice, and that these responses were mediated by Th-1 cells. Mice immunized with the vaccine had greater levels of protection against mortality following challenge with T. gondii RH tachyzoites than did those immunized with PBS or the empty vector control.
TgASP1 is a novel candidate DNA vaccine that merits further investigation.
刚地弓形虫是一种专性细胞内寄生虫，可引起弓形体病，对人类健康构成严重威胁。目前还没有针对这种感染的慢性囊泡期的药物，因此开发有效的疫苗将是一个重要的进展。天冬氨酸蛋白酶在刚地弓形虫的生命周期中发挥着重要作用。寄生虫有四个天冬氨酸蛋白酶编码基因，分别称为弓形虫蛋白酶 1、2、3 和 5（TgASP1、2、3 和 5）。
生物信息学方法使我们能够识别 TgASP1 上的几个有前途的线性 B 细胞表位和潜在的 Th 细胞表位，从而支持其作为弓形虫病 DNA 疫苗的潜力。我们在大肠杆菌中表达 TgASP1，并使用纯化的蛋白免疫 BALB/c 小鼠。获得的抗体用于确定 TgASP1 在寄生虫中的定位。我们还构建了 TgASP1 DNA 疫苗，并评估了它对感染强毒 RH 株刚地弓形虫的小鼠的保护水平。
TgASP1 似乎是一种主要位于刚地弓形虫速殖子顶端的膜蛋白。对其作为 DNA 疫苗的潜力的研究表明，它在小鼠中引起了强烈的体液和细胞免疫反应，这些反应是由 Th1 细胞介导的。与用 PBS 或空载体对照免疫的小鼠相比，用疫苗免疫的小鼠在感染刚地弓形虫 RH 速殖子后死亡率降低。
TgASP1 是一种新型候选 DNA 疫苗，值得进一步研究。
