A DNA Vaccine to Prevent Transmission of Human Malaria

描述（由申请方提供）：针对疟疾的传播阻断疫苗（TBV）旨在诱导针对感染蚊子的寄生虫阶段的免疫力，从而减少或停止疟疾传播。疟疾传播发生在局部和"局部"，即在空间上局限于传染源，因此在社区中使用TBV可以有效地抑制疟疾向他人的传播。TBV将诱导抗体，这些抗体将靶向疟疾寄生虫的有性阶段和蚊子中肠阶段表面上表达的抗原。靶抗原包括在配子母细胞中合成的蛋白质（受精前抗原，在恶性疟原虫中：Pfs 230和Pfs 48/45）和在受精卵-动合子中合成的蛋白质（受精后抗原，在恶性疟原虫中：Pfs 25和Pfs 28），并且由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性构象。不能表达正确折叠的蛋白质是严重阻碍基于蛋白质的TBV发展的主要因素之一。设想基于DNA的疫苗接种以克服重组蛋白中的构象问题，并且实际上在小鼠和猴子中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中评估受精前和受精后抗原的混合物。所提出的研究旨在（1）鉴定受精前抗原中的免疫学相关结构域，（2）通过阳离子脂质中的疫苗制剂和通过体内电穿孔的疫苗递送来优化受精前和受精后抗原的组合，（3）在非人灵长类动物中通过体内电穿孔评估候选DNA疫苗（Macaca mulatta），并使用用于恶性疟原虫感染的Aotus模型，测试针对受精前抗原的免疫可以通过在自然感染期间加强来维持的概念。此外，Pfs 25转基因伯氏疟原虫的开发将提供基于Pfs 25的人疟疾TBV的体内评价方法，与标准的体外膜喂养测定相比。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TBV用于人类志愿者的临床试验。

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.