Great Ape Reservoirs of Human Malaria

描述（由申请人提供）：之前R03申请的资助允许我们开发新的方法，允许从粪便DNA中扩增疟原虫序列。通过对中非50多个地点的猿类样本进行筛选，我们发现恶性疟原虫起源于大猩猩，而不是黑猩猩、倭黑猩猩或古人类。我们还发现，黑猩猩和大猩猩体内至少有9种疟原虫，其中包括与间日疟原虫、卵形疟原虫和疟疾疟原虫几乎相同的寄生虫。考虑到这个疟原虫储存库的规模，以及大猩猩恶性疟原虫已经通过物种传播给人类一次的事实，问题出现了，猿疟原虫是否正在发生其他交叉感染。这对公共卫生至关重要，不是因为这种传播预计会导致目前的疟疾发病率和死亡率，而是因为它们将表明，如果恶性疟原虫传播率的降低产生新的生态位，类人猿疟疾寄生虫可能会在人类中定居。在这个应用程序中，我们将研究野生猿是否作为人类疟疾的复发源。我们将继续筛查野生猿类种群的疟原虫感染情况，并对生活在这些猿类附近的人类进行跨物种感染证据测试。我们的假设是猿寄生虫有可能感染人类，但由于恶性疟原虫的优势而无法建立持续感染。确定类人猿跨物种疟原虫感染的类型、地点和频率对于衡量未来根除恶性疟原虫运动的成功与否至关重要。1. 目的确定间日疟原虫和其他非狐猴属物种在野生类人猿中的流行情况。我们将确定非狐猴寄生虫在野生猿类中的流行率、宿主特异性和分布，并确定黑猩猩和/或大猩猩是否代表西非中部人类间日疟原虫的储存库。确定野生黑猩猩或大猩猩是否作为人类感染的复发源。我们将使用超深（454）测序来筛选生活在野生猿类附近的人类，以寻找人畜共患疟原虫感染的证据。这种方法将识别lavania和非lavania寄生虫，即使它们以非常低的频率在多物种感染的情况下感染人类。3. 确定猿猴疟原虫感染的自然历史。我们将对受疟原虫感染的保护区猿类进行前瞻性随访，以检验其临床状况，验证我们的非侵入性检测方法，并获得猿类疟原虫分离和全基因组测序的血液样本。4. 目的：确定人类恶性疟原虫与类人猿的生物学特性。我们将表达类人猿疟原虫红细胞结合配体并测试其与人类红细胞结合的能力，以研究疟原虫宿主特异性的分子基础，并评估哪些类人猿疟原虫有能力引起人类血期感染。

DESCRIPTION (provided by applicant): Previous funding by an R03 application allowed us to develop novel methods that permit the amplification of Plasmodium sequences from fecal DNA. Screening ape samples from over 50 field sites throughout central Africa, we found that P. falciparum is of gorilla origin, and not of chimpanzee, bonobo or ancient human origin. We also found that chimpanzees and gorillas harbor at least nine Plasmodium species, including parasites that are near identical to P. vivax, P. ovale and P. malariae. Given the magnitude of this Plasmodium reservoir and the fact that gorilla P. falciparum has crossed the species to humans already once, the question arises whether additional cross-infections of ape Plasmodium parasites are occurring. This is of critical public health importance, not because such transmissions would be expected to contribute to current malaria morbidity and mortality, but because they would give an indication of the potential of ape malaria parasites to colonize humans should a reduction of P. falciparum transmission rates generate a new ecological niche. In this application, we will examine whether wild apes serve as a recurrent source of human malaria. We will continue to screen wild ape populations for Plasmodium infections, and test humans who live in close proximity to these apes for evidence of cross-species infection. Our hypothesis is that ape parasites have the potential to infect humans but fail to establish persistent infections because of the predominance of P. falciparum. Determining the types, locations and frequencies of ape Plasmodium cross-species infections will be critical to gauge the success of future P. falciparum eradication campaigns. 1. To determine the prevalence of P. vivax and other non-Laverania species in wild apes. We will determine the prevalence, host specificities and distribution of non-Laverania parasites in wild apes, and determine whether chimpanzees and/or gorillas represent a reservoir for human P. vivax in west central Africa. 2. To determine whether wild chimpanzees or gorillas serve as recurrent sources of human infection. We will use ultradeep (454) sequencing to screen humans who live in close proximity to wild apes for evidence of zoonotic Plasmodium infections. This approach will identify Laverania and non-Laverania parasites even if they infect humans at very low frequencies and in the context of multispecies infections. 3. To determine the natural history of ape Plasmodium infections. We will prospectively follow Plasmodium infected sanctuary apes to examine their clinical status, validate our non-invasive detection methods, and obtain blood samples for ape Plasmodium isolation and whole genome sequencing studies. 4. To determine the biological properties that distinguish human P. falciparum from related ape species. We will express ape Plasmodium erythrocyte binding ligands and test their ability to bind to human erythrocytes in order to investigate the molecular basis of Plasmodium host specificity and to assess which ape Plasmodium species have the capacity to cause a blood stage infection in humans.