Variant surface glycoprotein diversification in Trypanosoma brucei

布氏锥虫表面糖蛋白变异多样化

基本信息

批准号：
9211653
负责人：
Monica Mugnier
金额：
$ 40.5万
依托单位：
JOHNS HOPKINS UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-09-19 至 2021-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9211653
关键词：
Affect Africa South of the Sahara African Trypanosomiasis Animals Antibodies Antibody Response Antigenic Variation Antigens Archives Area Bioinformatics Blood CRISPR/Cas technology Cell surface Chronic DNA Data Development Disease Economic Burden Event Evolution Gene Conversion Generations Genes Genetic Recombination Genomics Goals High-Throughput Nucleotide Sequencing Human Immune Immune response Immune system Individual Infection Lead Left Life Location Maintenance Masks Measures Membrane Glycoproteins Methods Mus Mutation Parasitemia Parasites Pattern Pattern Formation Pharmaceutical Preparations Population Positioning Attribute Process Public Health Resolution Role Somatic Mutation System Technology Textbooks Therapeutic Time Tissues Tropical Disease Trypanosoma Trypanosoma brucei brucei Trypanosomiasis Variant Work extracellular genetic variant human disease in vivo insight interest nagana neglected tropical diseases new therapeutic target novel parasite genome pathogen pressure research study tool treatment strategy

项目摘要

PROJECT SUMMARY Trypanosoma brucei is a causative agent of both human and animal African trypanosomiasis, devastating diseases affecting sub-Saharan Africa. A dense variant surface glycoprotein (VSG) coat covers this extracellular parasite and effectively masks all other antigens on the cell surface. T. brucei evades elimination by the mammalian host's immune system through antigenic variation of its VSG coat: it “switches” the expressed VSG, taking advantage of a genomic repertoire of ~2000 VSG-encoding genes. However, parasite populations in vivo express a diverse set of VSG-encoding genes. The number of expressed VSGs over 30 days of infection can approach one-third of the functional VSG repertoire within the parasite genome, which highlights an interesting question: if the existing genomic repertoire can be used up in a matter of months, how can an infection be sustained for years in the field? The goal of this application is to investigate the mechanisms by which T. brucei diversifies its genomic VSG repertoire in order to sustain infection. Preliminary data suggest that extravascular spaces may provide an important area for T. brucei to diversify its VSG archive in the absence of immune pressure. In the first aim of this proposal, the role of this extravascular niche in VSG diversification will be investigated. The second aim will take advantage of CRISPR/Cas9 technology combined with a novel high-throughput sequencing method to investigate the segmental gene conversion events resulting in novel “mosaic” VSGs. In the third aim, the mutation of individual VSGs will be studied, in order to understand the mechanisms that govern the evolution of the VSG archive within the parasite genome over the course of infection. These studies will begin to elucidate the mechanisms by which T. brucei sustains a long- term infection in its host, which will be important for the development of new strategies for treatment of this neglected tropical disease. Three aims are proposed to accomplish these goals: 1) To elucidate the role of extravascular spaces in VSG diversification; 2) To identify the mechanisms responsible for the segmental gene conversion events that generate mosaic VSGs; 3) To quantify the rate of hypermutation of VSGs.

项目概要布氏锥虫是人类和动物非洲锥虫病的病原体，具有毁灭性影响撒哈拉以南非洲的疾病。致密的变异表面糖蛋白（VSG）外套覆盖了它。细胞外寄生虫并有效掩盖细胞表面的所有其他抗原，从而逃避消除。哺乳动物宿主的免疫系统通过其 VSG 外壳的抗原变异：“切换” 表达 VSG，利用约 2000 个 VSG 编码基因的基因组库。体内群体表达多种 VSG 编码基因，表达的 VSG 数量超过 30 个。感染天数可以接近寄生虫基因组内功能 VSG 库的三分之一，这突出了一个有趣的问题：如果现有的基因组库可以在几个月内用完，那么如何感染可以在现场持续数年吗？本应用的目的是调查 T. brucei 使其基因组 VSG 库多样化以维持感染的机制。数据表明，血管外空间可能为 T. brucei 提供一个重要的区域，使其 VSG 档案多样化在没有免疫压力的情况下，该提案的第一个目标是研究 VSG 中血管外生态位的作用。第二个目标将利用 CRISPR/Cas9 技术的结合进行研究。采用新颖的高通量测序方法来研究片段基因转换事件产生新的“马赛克”VSG 在第三个目标中，将研究单个 VSG 的突变，以便了解控制寄生虫基因组内 VSG 档案进化的机制这些研究将开始阐明布氏锥虫维持长期感染的机制。宿主的足月感染，这对于制定治疗这种疾病的新策略非常重要为实现这些目标，提出了三个目标： 1) 阐明被忽视的热带病的作用。 VSG 多样化中的血管外空间；2) 确定节段基因的机制；产生马赛克 VSG 的转换事件；3) 量化 VSG 的超突变率。