A DNA Vaccine to Prevent Transmission of Human Malaria

描述(申请人提供)：针对疟疾的传播阻断疫苗(TBV)旨在诱导对感染蚊子的寄生虫阶段的免疫力，从而减少或阻止疟疾传播。疟疾传播是局部的和“局部的”传播，即在空间上局限于一个感染源，因此在一个社区使用的TBV可以有效地抑制疟疾向其他社区的传播。TBV将诱导抗体，这些抗体将针对疟疾寄生虫性寄生虫和蚊子中肠阶段表面表达的抗原。靶抗原包括在配子体(受精前抗原，恶性疟原虫：Pfs230和Pfs48/45)和受精卵-卵子(受精后抗原，恶性疟原虫：Pfs25和Pfs28)中合成的蛋白质，传递阻断抗体识别的表位本质上是富含半胱氨酸的还原敏感构象。不能表达正确的折叠蛋白是严重阻碍基于蛋白质的TBV发展的主要因素之一。基于DNA的疫苗被设想用来克服重组蛋白的构象问题，事实上，在小鼠和猴子身上的研究已经牢固地确立了基于DNA的TBV方法的价值。该疫苗平台可以促进在临床前环境下对受精前后抗原的鸡尾酒进行评估。建议的研究目标是：(1)识别受精前抗原中的免疫相关结构域；(2)通过阳离子脂类疫苗配方和体内电穿孔疫苗递送优化受精前后抗原的组合；(3)通过体内电穿孔在非人灵长类动物(Macaca Mulatta)体内评价候选DNA疫苗，并使用恶性疟原虫感染的Aotus模型检验自然感染期间通过增强对受精前抗原的免疫力这一概念。此外，Pfs25转基因伯氏疟原虫的建立将为基于Pfs25的人疟疾TBV的体内评估提供一种方法，与标准的体外膜喂养试验相比。这些都是关键和基本的问题，需要在临床前研究中系统地解决，然后才能开发出理想和有效的用于人体志愿者临床试验的TBV。

DESCRIPTION (provided by applicant): Transmission blocking vaccines (TBVs) against malaria are intended to induce immunity against the stages of the parasite that infect mosquitoes so that malaria transmission is reduced or halted. Malaria transmission occurs locally and 'focally', i.e. spatially confined to an infectious source, thus TBVs used in a community can effectively suppress malaria transmission to others. TBVs will induce antibodies that will target antigens expressed on the surface of sexual and mosquito midgut stages of the malaria parasite. The target antigens include proteins synthesized in the gametocytes (pre-fertilization antigens, in P. falciparum: Pfs230 and Pfs48/45) and in the zygotes-ookinetes (post-fertilization antigens, in P. falciparum: Pfs25 and Pfs28) and the epitopes recognized by transmission blocking antibodies are cysteine-rich reduction-sensitive conformational in nature. The inability to express properly folded proteins is one of the major factors that have severely hampered protein based TBV development. DNA based vaccination was envisaged to overcome the conformational problem in recombinant proteins, and indeed studies in mice and monkeys have firmly established the value of DNA based TBV approach. This vaccine platform can facilitate evaluation of a cocktail of pre- and post-fertilization antigens in pre clinical setting. Studies proposed are aimed at (1) identifying immunologically relevant domains in the pre-fertilization antigens, (2) optimizing the combination of pre- and post-fertilization antigens by vaccine formulation in cationic lipids and vaccine delivery by in vivo electroporation, (3) evaluating a candidate DNA vaccine by in vivo electroporation in nonhuman primates (Macaca mulatta) and testing the concept that immunity against pre-fertilization antigens can be maintained by boosting during natural infection using an Aotus model for P. falciparum infection. Moreover, the development of Pfs25 transgenic P. berghei will provide an approach for in vivo evaluation of human malaria TBV based on Pfs25, as compared to a standard in vitro membrane feeding assay. These are critical and essential issues that need to be systematically addressed in pre clinical studies prior to the development of an ideal and effective TBV for clinical trials in human volunteers.