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Malaria Parasite Sexual Development, Drug Resistance, and Evolution

疟疾寄生虫的性发育、耐药性和进化

基本信息

批准号：
7732562
负责人：
Xinzhuan Su
金额：
$ 104.06万
依托单位：
NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

项目摘要

In the past year, we have finished developing and evaluating two microarray platforms for large-scale genotyping of P. falciparum parasite. Using single nucleotide polymorphism (SNP) we collected in previous year, we have developed an array using Molecular Inversion Probe (MIP) technology and used the array to type more than 100 parasites. We also evaluated a tiling array for SNP detection and gene copy number variation. We showed that the tiling array was an excellent tool for genotyping too. Both arrays have been used to type parasite genomes. We are testing parasite responses to different antimalrial drugs to identify genes that may contribute to drug resistance. This study is expected to identify some candidate genes that can be further tested using other methods such as genetic modification of the genes. For example, we showed that several transporters were associated with higher levels of resistance to CQ and QN in one of our previous studies. Now we have disrupted one of the candidate genes and showed that it indeed could affect parasite response to both CQ and QN. We have finished testing the knockout parasites for their responses to drugs and other chemicals. The resources developed from this study will be useful for studying other parasite phenotypes. Mutations in drug resistance gene are often deleterious; and parasite can respond to the mutations with compensatory changes in their genome in order to survive. We used mcicroarray to search for genes that changed in expression after mutations in the key CQ resistant gene (pfcrt). A list of genes that changed in expression levels and in copy number were identified in parasite that had mutations in pfcrt. Another important issue associated with association mapping is accurate phenotyping. We investigated how mixed infections (often seen in field samples) of drug resistant and sensitive parasites affect drug test results. We found that a mixture of 10% (or more) resistant parasite in a sensitive population could greatly affect drug test results, providing important information for drug tests in the field. Last year, we found that P. vivax parasites in Southern Mexico consist of three subpopulations that had strong mosquito vector preferences. Identification of molecules that mediate mosquito specificity may provide critical information for transmission control. We have genotyped hundreds of more parasite samples and are investigating the relationship of genotypes and relapse/re-infections to better understand parasite transmission dynamics. We are also interested in gene regulation mechanisms such as chromatin modification or microRNA mediated mechanisms.

去年，我们完成了两个用于恶性疟原虫大规模基因分型的微阵列平台的开发和评估。利用我们去年收集的单核苷酸多态性（SNP），我们开发了一种采用分子倒置探针（MIP）技术的芯片，并使用该芯片对100多种寄生虫进行了分型。我们还评估了用于 SNP 检测和基因拷贝数变异的平铺阵列。我们证明平铺阵列也是基因分型的绝佳工具。两种阵列均已用于对寄生虫基因组进行分型。我们正在测试寄生虫对不同抗疟药物的反应，以确定可能导致耐药性的基因。这项研究预计将确定一些候选基因，这些基因可以使用其他方法（例如基因的遗传修饰）进一步测试。例如，我们在之前的一项研究中表明，几种转运蛋白与较高水平的 CQ 和 QN 耐药性相关。现在我们已经破坏了其中一个候选基因，并表明它确实可以影响寄生虫对 CQ 和 QN 的反应。我们已经完成了基因敲除寄生虫对药物和其他化学物质反应的测试。这项研究开发的资源将有助于研究其他寄生虫表型。耐药基因突变通常是有害的；寄生虫可以通过基因组的补偿性变化来应对突变，以求生存。我们使用微阵列来寻找关键 CQ 抗性基因 (pfcrt) 突变后表达发生变化的基因。在 pfcrt 发生突变的寄生虫中鉴定出一系列表达水平和拷贝数发生变化的基因。与关联作图相关的另一个重要问题是准确的表型分析。我们研究了耐药性和敏感寄生虫的混合感染（常见于现场样本）如何影响药物测试结果。我们发现，敏感人群中10%（或更多）耐药寄生虫的混合物可能会极大地影响药物测试结果，为现场药物测试提供重要信息。去年，我们发现墨西哥南部的间日疟原虫由三个对蚊子媒介具有强烈偏好的亚群组成。介导蚊子特异性的分子的鉴定可能为传播控制提供关键信息。我们已经对数百个寄生虫样本进行了基因分型，并正在研究基因型与复发/再感染的关系，以更好地了解寄生虫传播动态。我们还对基因调控机制感兴趣，例如染色质修饰或 microRNA 介导的机制。