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：
9933496
负责人：
Monica Mugnier
金额：
$ 7.91万
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 2020-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9933496
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 Drug Targeting Economic Burden Event Evolution Gene Conversion Generations Genes Genetic Recombination Genomics Goals High-Throughput Nucleotide Sequencing Human Immune Immune Evasion Immune response Immune system Individual Infection Lead Left Location Maintenance Masks Measures Membrane Glycoproteins Methods Mosaicism Mus Mutation Parasitemia Parasites Pattern Periodicity 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 Zoonoses chronic infection experimental study extracellular genetic variant human disease in vivo insight nagana neglected tropical diseases novel parasite genome pathogen pressure 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.

项目摘要布鲁氏锥虫是人和动物非洲锥虫病的原因，毁灭性的影响撒哈拉以南非洲的疾病。致密的变体表面糖蛋白（VSG）外套覆盖了细胞外寄生虫，有效地掩盖了细胞表面上的所有其他抗原。 T. Brucei Evades淘汰通过哺乳动物宿主的免疫系统通过其VSG外套的抗原变异：它“切换” 表达VSG，利用了〜2000 VSG编码基因的基因组曲目。但是，寄生虫体内人群表达了一组VSG编码的基因。超过30的表达VSG的数量感染日可以接近寄生虫基因组中功能性VSG库的三分之一，而寄生虫基因组中突出一个有趣的问题：现有的基因组曲目是否可以在几个月内用完感染能在该领域持续多年吗？此应用的目的是调查为了维持感染，T. Brucei多样化其基因组VSG曲目的机制。初步的数据表明，血管外空间可能为T. Brucei多样化其VSG存档提供了重要的领域在没有免疫压力的情况下。在该提议的第一个目的中，这种血管外生态位在VSG中的作用多元化将被调查。第二个目标将利用CRISPR/CAS9技术的总和采用一种新型的高通量测序方法来研究分段基因转换事件导致新颖的“马赛克” VSG。在第三个目标中，单个VSG的突变将研究，以便为了了解控制寄生虫基因组中VSG档案演变的机制感染过程。这些研究将开始阐明t. t. brucei持续的机制宿主中的期限感染，这对于制定新的策略很重要被忽视的热带疾病。提出了三个目标来实现这些目标：1）阐明 VSG多样化的血管外空间； 2）确定负责分段基因的机制产生马赛克VSG的转换事件； 3）量化VSGS的超名速率。