Molecular epidemiology of Plasmodium reichenowi

描述（由申请人提供）：四种疟原虫引起人类疟疾，但恶性疟原虫是几乎所有人类疟疾死亡的罪魁祸首，每年导致100多万人死亡。然而，恶性疟原虫与引起人类疟疾的其他三种疟原虫只有远亲关系，而黑猩猩和大猩猩的疟原虫雷氏疟原虫在形态上与恶性疟原虫几乎无法区分。这种非常密切的关系已被分子系统发育研究证实，因此，雷氏疟原虫序列是恶性疟原虫遗传多样性研究中非常强大的外群，旨在识别免疫选择压力下的恶性疟原虫基因。这两种生物之间的相似之处对理解恶性疟原虫发病机制的具体方面也有很大的兴趣。然而，尽管20世纪初在野生黑猩猩的血液中多次观察到疟原虫，但科学界只获得过一种疟原虫分离物，而且这种分离物的冷冻试管也只保存在疾病预防控制中心。虽然一些有限的p.r ichenowi基因组序列是可用的，使用这些冷冻库存生成的，但它主要由短片段组成，并且受到黑猩猩DNA的严重污染。在找到新的赖氏疟原虫DNA来源之前，对赖氏疟原虫基因组的研究工作已经停止。因此，迫切需要新的赖氏疟原虫分离株来完成赖氏疟原虫的基因组序列，并进行比较遗传和发病机制的研究。为了获得新的雷氏疟原虫分离株，我们需要鉴定发生雷氏疟原虫感染的野生黑猩猩种群，但从未开展过雷氏疟原虫在野生黑猩猩中的流行研究。黑猩猩的受保护地位严格限制了此类研究所能获得的样本。本应用程序的目的是采用一种独特的，非侵入性和伦理敏感的测定方法来确定野生黑猩猩群落中雷氏疟原虫感染的流行程度。为了实现这一目标，我们开发了一种使用尿液样本检测疟原虫感染的新型检测方法。我们建议将这种分析应用于黑猩猩尿液和粪便样本的独特和预先存在的收集。我们的具体目标是：1。建立使用尿液样本检测过去疟原虫感染的敏感性。2. 确定雷氏疟原虫在野生黑猩猩种群中的流行和分布。该项目有望首次确定野生黑猩猩中雷氏疟原虫感染的流行和分布。预计它还将直接导致鉴定新的雷氏疟原虫分离株，这些分离株将免费提供给疟疾研究界。这些分离物将是了解最重要的人类传染病杀手之一恶性疟原虫的进化和发病机制的杰出和独特的资源。恶性疟原虫每年导致100多万人死亡。为了了解恶性疟原虫的毒力和致病性，我们需要将其与密切相关的寄生虫物种进行比较，但与恶性疟原虫最密切相关的寄生虫，一种叫做P. reichenowi的黑猩猩寄生虫，只被分离过一次，而且这种分离物的数量有限。该应用程序的目的是确定野生黑猩猩中疟原虫感染的流行程度，并利用该信息获得新的疟原虫分离株，这些分离株将提供给疟疾研究界进行比较研究。

DESCRIPTION (provided by applicant): Four species of Plasmodium parasites cause malaria in humans, but Plasmodium falciparum is responsible for almost all human malaria mortality, killing more than 1 million people each year. However P. falciparum is only distantly related to the other three Plasmodium species that cause malaria in humans, whereas P. reichenowi, a parasite of chimpanzees and gorillas, is morphologically almost indistinguishable from P. falciparum. This remarkably close relationship has been confirmed by molecular phylogenetic studies and P. reichenowi sequences are therefore very powerful outgroups for P. falciparum genetic diversity studies aimed at identifying P. falciparum genes under immune selection pressure. The parallels between the organisms are also of great interest in understanding specific aspects of P. falciparum pathogenesis. However, although P. reichenowi was observed in the blood of wild chimpanzees on several occasions in the early 20th century, only a single P. reichenowi isolate has ever been obtained by the scientific community, and only a handful of frozen tubes of that isolate remain at CDC. Although some limited P. reichenowi genome sequence is available, generated using these frozen stocks, it consists largely of short fragments and is heavily contaminated with chimpanzee DNA. Work on the P. reichenowi genome has ceased until new sources of P. reichenowi DNA can be found. New P. reichenowi isolates are therefore urgently needed to complete the P. reichenowi genome sequence, as well as for comparative genetic and pathogenesis studies. In order to obtain new P. reichenowi isolates we need to identify wild chimpanzee populations in which P. reichenowi infections occur, but no prevalence study of P. reichenowi infection in wild chimpanzees has ever been carried out. The protected status of chimpanzees places strict limits on the samples that can be obtained for such studies. The objective of this application is to employ a unique, non-invasive and ethically sensitive assay to establish the prevalence of P. reichenowi infection in wild chimpanzee communities. To achieve this objective we have developed a novel assay that uses urine samples to detect Plasmodium infection. We propose to apply this assay to a unique and pre-existing collection of chimpanzee urine and fecal samples. Our specific aims are: 1. Establish the sensitivity of using urine samples to detect past Plasmodium infections. 2. Establish the prevalence and distribution of P. reichenowi in wild chimpanzee populations. This project is expected to define for the first time the prevalence and distribution of P. reichenowi infection in wild chimpanzees. It is also expected to lead directly to the identification of new P. reichenowi isolates that would be made freely available to the malaria research community. Such isolates would be an outstanding and unique resource for understanding of the evolution and pathogenesis of one of the most important human infectious disease killers, Plasmodium falciparum. Plasmodium falciparum parasites kill more than 1 million people each year. In order to understand P. falciparum virulence and pathogenicity we need to compare it with closely related parasite species, but the parasite most closely related to P. falciparum, a chimpanzee parasite called P. reichenowi, has only ever been isolated once and only limited stocks of that isolate remain. The objective of this application is to establish the prevalence of P. reichenowi infection in wild chimpanzees and to use that information to obtain new P. reichenowi isolates that would be made available to the malaria research community for comparative studies.