FOSMIDOMYCIN RESISTANCE IN PLASMODIUM FALCIPARUM

恶性疟原虫对磷米霉素的耐药性

• 批准号: 8420970
• 负责人: Audrey Ragan Odom John
• 金额: $ 31.56万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-12-01 至 2017-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8420970
• 关键词: Anabolism; Antimalarials; Antiparasitic Agents; Artemisinins; Biochemical; Biochemical Genetics; Biochemical Pathway; Biological; Biological Markers; Biology; Cessation of life; Chemicals; Chloroquine resistance; Clinical Trials; Collection; Combined Modality Therapy; Data; Development; Diagnostic; Disease; Drug Targeting; Drug resistance; Electron Transport; Enzymes; Future; Genes; Genetic; Genetic Engineering; Genome; Goals; Gram-Negative Bacteria; Health; Human; Knowledge; Lead; Malaria; Metabolic; Metabolic Pathway; Metabolism; Molecular; Mutation; Mycobacterium tuberculosis; Parasites; Pathway interactions; Pharmaceutical Preparations; Phase; Phase II Clinical Trials; Plasmodium falciparum; Process; Protein Isoprenylation; Public Health; Regulation; Research; Resistance; Signal Transduction; Signs and Symptoms; Validation; antimicrobial drug; artemisinine; base; drug development; fosmidomycin; gene replacement; genetic analysis; genome sequencing; improved; inhibitor/antagonist; innovation; isoprenoid; killings; meetings; mutant; next generation; next generation sequencing; novel; pathogen; positional cloning; prenylation; protein metabolism; public health relevance; resistance mutation; resistant strain; small molecule

DESCRIPTION (provided by applicant): Plasmodium falciparum is a protozoan pathogen that causes the deadliest form of malaria. Malaria has a tremendous impact on human health worldwide, causing nearly one million deaths per year. New therapies are urgently needed to treat this disease, due to widespread chloroquine resistance and emerging resistance to artemisinins. P. falciparum possesses an essential metabolic pathway, non-mevalonate isoprenoid biosynthesis (the MEP pathway), which is not present in humans. This pathway is a particularly enticing antimalarial drug target because it is shared by other important human pathogens, including Gram-negative bacteria and Mycobacterium tuberculosis. The long-term goal is to understand why isoprenoids are essential in malaria parasites. Fosmidomycin is a validated inhibitor of the MEP pathway and is currently in Phase II clinical trials of combination therapy to treat malaria. In preliminary studies, a collection of fosmidomycin-resistant malaria parasites have been developed that not only lack mutations in the known targets of this drug but also continue to grow even when isoprenoid biosynthesis is inhibited. These fosmidomycin-resistant strains presumably survive through genetic changes in a "rescue pathway." The objective of this proposal is to determine the biochemical and genetic mechanisms by which these parasites have become resistant. The rationale for these studies is that identification of the genes and pathways that genetically interact with fosmidomycin will inform the regulation and downstream biology of isoprenoid biosynthesis in P. falciparum. Understanding how fosmidomycin-resistant malaria strains survive, despite inhibition of isoprenoid biosynthesis, will elucidate why isoprenoids are typically essential. This approach takes advantage of a pathogen-specific biochemical pathway and a potent chemical inhibitor of isoprenoid biosynthesis that is already in clinical trials. Supported by strong preliminary data that indicate that this strategy wll be successful, the objectives will be met through three specific aims: 1) metabolic analysis of MEP metabolism and protein prenylation (an important function of isoprenoid biosynthesis) in fosmidomycin-resistant malaria parasites; 2) genetic analysis of fosmidomycin-resistant malaria parasites through next-generation sequencing strategies; and 3) identification of the genetic changes that confer fosmidomycin resistance, by recapitulating candidate resistance mutations in sensitive wild-type parasite lines. This approach is innovative, since it uses genetic characterization of drug-resistant malaria parasites not only for drug target validation, but also o expand the fundamental biological understanding of an essential metabolic pathway. The proposed research is significant, because it will identify diagnostic biomarkers of fosmidomycin resistance, improve functional annotation of "hypothetical" genes in the P. falciparum genome, and identify new targets for much-needed antimalarial drug development.

描述(申请人提供)：恶性疟原虫是一种原生动物病原体，可导致最致命的疟疾。疟疾在世界范围内对人类健康造成巨大影响，每年造成近100万人死亡。由于广泛的氯喹耐药性和对青蒿素的新耐药性，迫切需要新的疗法来治疗这种疾病。恶性疟原虫有一种重要的代谢途径，即非甲氧戊酸类异戊二烯生物合成(MEP途径)，这是人类所没有的。这一途径是一个特别诱人的抗疟疾药物靶点，因为它与其他重要的人类病原体相同，包括革兰氏阴性细菌和结核分枝杆菌。长期目标是了解为什么类异戊二烯在疟疾寄生虫中是必不可少的。磷霉素是MEP途径的有效抑制剂，目前正处于联合疗法治疗疟疾的第二阶段临床试验中。在初步研究中，已经开发出一系列对磷霉素具有抗药性的疟疾寄生虫，这些寄生虫不仅在这种药物的已知靶标中缺乏突变，而且即使在类异戊二烯的生物合成受到抑制的情况下也会继续生长。据推测，这些耐药菌株可能通过“挽救途径”中的基因变化存活下来。这项建议的目标是确定这些寄生虫产生抗药性的生化和遗传机制。这些研究的基本原理是，识别与磷霉素在遗传上相互作用的基因和途径将为恶性疟原虫类异戊二烯生物合成的调控和下游生物学提供信息。尽管类异戊二烯的生物合成受到抑制，但理解耐药疟疾菌株是如何存活的，这将是 解释为什么异戊二烯类化合物通常是必需的。这种方法利用了病原体特有的生化途径和一种已经在临床试验中的类异戊二烯生物合成的有效化学抑制剂。在表明这一策略将成功的强有力的初步数据的支持下，这些目标将通过三个具体目标来实现：1)对耐磷霉素型疟疾寄生虫进行MEP代谢和蛋白质戊二烯基化(类异戊二烯生物合成的重要功能)的代谢分析；2)通过下一代测序策略对抗磷霉素型疟疾寄生虫进行遗传分析；以及3)通过概括敏感野生型寄生虫株中的候选耐药突变来鉴定与磷霉素类抗药性有关的基因变化。这种方法是创新的，因为它不仅使用抗药性疟疾寄生虫的基因特征来验证药物靶标，而且还扩大了对基本代谢途径的基本生物学理解。这项拟议的研究具有重要意义，因为它将识别磷霉素耐药性的诊断生物标记物，改进恶性疟原虫基因组中“假设”基因的功能注释，并为亟需的抗疟疾药物开发确定新的靶点。