Variant surface antigens in cerebral malaria pathogenesis

 描述(申请人提供)：脑型疟疾是最致命的疟疾形式，可能导致一半的受害者--主要是撒哈拉以南非洲的儿童--死亡。然而，疟疾流行地区的大多数儿童似乎在生命早期就对严重疟疾产生了免疫力，这种现象与疟疾寄生虫抗原抗体的产生有关，这些抗体表达在受感染的红细胞表面。这些变异的表面抗原(VSA)是寄生虫基因组中最具多态性的家族：恶性疟原虫红细胞膜蛋白(PfEMP1)、重复散布家族蛋白(RIFINs)和亚端粒可变开放阅读框蛋白(STEVORs)。每个疟疾基因组都有数百个基因编码这些不同的寄生虫表面抗原，其中只有一小部分表达在给定的受感染红细胞的表面。如果VSA的一个子集是针对脑型疟疾的，它们将成为疟疾疫苗的重要目标，以保护儿童和旅行者免受疟疾最致命的后果。我们在马里农村的实地研究表明，疟疾寄生虫表达这些寄生虫表面抗原的一个“隐形”亚群，在脑型疟疾中比在较轻形式的疟疾中更常见。我们的总体目标是确定VSA对脑型疟疾病理生理学的贡献，以及个体发展VSA抗体在获得对脑型疟疾的免疫力方面的重要性。该项目将新的基因组和蛋白质组方法与新的动物模型相结合，以衡量特定变异表面抗原与脑型疟疾的发展之间的联系，并保护自然免疫。我们将在脑疟疾病例对照研究中确定脑型疟疾感染和匹配的无并发症疟疾对照中的VSA的基因序列，并确定在受感染的红细胞表面发现哪些VSA(目标1)。小鼠将感染这些来自野外的寄生虫，将在大脑中确定微血管的病理生理效应，包括与VSA表达的关联(目标2)。多个VSA片段将被编码到微阵列芯片上，然后将其暴露在患者的血清中，以同时研究抗体与所有这些蛋白质的相互作用(目标3)。该项目引入了尖端研究技术--一些来自疟疾研究界以外的技术--包括下一代测序、定制微阵列、蛋白质组学和一个有前途的新动物模型，以促进我们对脑型疟疾的理解和脑型疟疾疫苗的开发。

 DESCRIPTION (provided by applicant): Cerebral malaria is the deadliest form of malaria, potentially killing half of its victims-primarily children in sub- Saharan Africa. However, most children in malaria-endemic regions appear to develop immunity to severe malaria early in life, a phenomenon that correlates with the production of antibodies to malaria parasite antigens that are expressed on the surface of infected erythrocytes. These variant surface antigens (VSAs) are the most polymorphic families within the parasite genome: Plasmodium falciparum erythrocyte membrane proteins (PfEMP1), repetitive interspersed family proteins (RIFINs) and the sub-telomeric variable open reading frame proteins (STEVORs). Each malaria genome has hundreds of genes encoding these diverse parasite surface antigens, of which only a small subset are expressed on the surface of a given infected erythrocyte. If a subset of VSAs is specific to cerebral malaria, they would be an important target for a malaria vaccine to protect children and travelers from the deadliest consequences of malaria. Work at our field site in rural Mali suggests that malaria parasites express a "stealth" subgroup of these parasite surface antigens more commonly in cerebral malaria than in milder forms of malaria. Our overall goals are to determine the VSA contribution to the pathophysiology of cerebral malaria and the importance of an individual's development of antibodies to VSAs in the acquisition of immunity to cerebral malaria. This project combines novel genomic and proteomic approaches with the use of a new animal model to measure the association between particular variant surface antigens and the development of cerebral malaria and also protective natural immunity. We will determine the genetic sequences of VSAs in cerebral malaria infections and in matched uncomplicated malaria controls in a cerebral malaria case-control study and ascertain which VSAs are found on the surface on infected erythrocytes (Aim 1). Mice will be infected with these field-derived parasites and the microvascular pathophysiological effects will be identified in the brain, including associations with expressed VSAs (Aim 2). Multiple VSA fragments will be encoded onto microarray chips, which will then be exposed to patients' sera to study antibody interactions with all of these proteins at once (Aim 3). This project introduces cutting-edge research techniques-some from outside the malaria research community-including next-generation sequencing, custom microarrays, proteomics, and a promising new animal model, to advance our understanding of cerebral malaria and the development of a cerebral malaria vaccine.