疟原虫QSOX生物学功能及其传播阻断潜能的研究

疟疾是严重威胁人类健康的感染性寄生虫病。传播阻断疫苗（TBV）对控制疟疾特别是间日疟的流行意义重大，而候选抗原的发掘及其在疟原虫发育阶段功能的阐明是TBV研发的关键。静息巯基氧化酶（QSOX）是催化生物体二硫键正确形成、促进蛋白质发挥生理活性的关键酶类，但迄今为止疟原虫QSOX的生物学特点及功能尚未阐明。我们在前期研究中筛选确定了疟原虫QSOX，阐明了其在疟原虫有性生殖阶段表面表达，并初步证明了其抗血清的传播阻断能力，提示QSOX具有成为TBV候选抗原的潜能。本项目拟对疟原虫QSOX的生物学功能进行系统研究，利用基因重组技术揭示QSOX对疟原虫生长发育的影响；通过重组蛋白的表达明确酶活性特点，并确定酶抑制剂对疟原虫发育的影响；制备免疫血清与单克隆抗体，通过鼠疟模型与间日疟膜饲实验系统验证QSOX的传播阻断活性。以期寻求间日疟原虫防控的新靶位，为研发新型、高效的TBV抗原提供理论与实验依据。

Malaria is one of the parasitic diseases which severely impairs humanity health. Transmission blocking vaccine (TBV) plays an essential role in malaria elimination, especially Plasmodium vivax malaria. The discovery of TBV candidate and clarify its functions in the malaria parasite development stage are prerequisite for TBV studies. The enzyme family Quiescin Sulfhydryl Oxidase (QSOX), which catalyzes generate disulfide bonds into unfolded reduced proteins, is vital for proteins to play a physiological activity. Nonetheless, the existence and functions of QSOX in Plasmodium are still unknown. Based on the significance of TBV control the spread of Plasmodium and the current research situation of Plasmodium QSOX, in our previous study, we identified a QSOX member in Plasmodium. The expression of QSOX was only detected on the surface in sexual stages and antisera against this recombinant QSOX antigen possessed strong transmission blocking activity. We therefore postulate that Plasmodium QSOX may be a potential candidate antigen for TBV. The project intends to use parasite transfection technology to knock out qsox gene in Plasmodium berghei ANKA model and study the functions during parasite development. By expression of QSOX recombinant protein, we will further clarify the characteristic of the enzyme activity, identify the enzyme inhibitor and detail analysis its effect on parasite development. Further, we will also obtain antisera and monoclonal antibody, systematic evaluation of the transmission blocking activities both in Plasmodium berghei and Plasmodium vivax model. This study will reveal the parasite developmental mechanism of QSOX in sexual stage, and expect to provide a new theoretical and experimental basis for the development of an effective Plasmodium vivax malaria vaccine.