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Using Legionella-amoeba co-evolution to reveal new modes of immunity and pathogenesis

利用军团菌-阿米巴共同进化揭示新的免疫模式和发病机制

基本信息

批准号：
10200673
负责人：
Tera Catherine Levin
金额：
$ 31.64万
依托单位：
UNIVERSITY OF PITTSBURGH AT PITTSBURGH
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-01 至 2023-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10200673
关键词：
Address Amoeba genus Animals Anti-Bacterial Agents Antibiotics Attention Bacteria Bacterial Genes Bacterial Infections Bacteriology Biological Models Biology Candidate Disease Gene Cells Cellular biology Conflict (Psychology)Cytosol Detection Dictyostelium Disease Disease Outbreaks Environment Eukaryotic Cell Evolution Genes Genetic Genetic Screening Genetic Transcription Genome Genomics Health Human Immune Immune response Immune system Immunity Infection Iron Lead Legionella Legionella pneumophila Mammalian Cell Microbe Modeling Molecular Molecular Evolution Natural Immunity Organism Outcome Pathogenesis Pathway interactions Play Pneumonia Predisposition Proteins Race Research Resources Role Structure System Testing Toll-like receptors Training Transgenic Organisms Viral Pathogenesis arm bacterial fitness bacterial genetics base comparative genomics experience experimental study fighting fitness genetic approach genetic evolution genome-wide genome-wide analysis host-microbe interactions imprint innovation interdisciplinary approach man member microbial molecular shape mutant novel novel strategies opportunistic pathogen pathogen pathogen genome pathogenic bacteria pressure prevent programs residence transposon sequencing

项目摘要

PROJECT SUMMARY Legionella pneumophila is an opportunistic bacterial pathogen that causes outbreaks of a lethal, pneumonia- like disease. Although human infections are evolutionary “dead ends” for these bacteria, Legionella nevertheless carry extensive molecular arsenals to attack human cells due to their adaptation to their natural hosts, environmental amoebae. Residence in amoebae also protects Legionella from antibiotics and other efforts to eliminate the bacteria from man-made structures, perpetuating human outbreaks. Revealing how Legionella exploits host amoebae—particularly steps vulnerable to disruption—therefore has direct benefits for human health. This proposal will investigate how molecular “arms races” between Legionella and amoebae have shaped the molecular toolkit of this pathogen, and address the specific hypothesis that Legionella secreted effector proteins are engaged in arms races with amoeba immune pathways. The experimental tractability and evolutionary resources available for Legionella and amoebae make this a powerful host- microbe model system, where it is possible to test the functional consequences of evolutionary innovation in both host and microbe. Aim 1 will investigate how Legionella has been impacted by such an arms race. Evolutionary approaches will analyze this organism's enormous arsenal of molecular weaponry, the type IV effectors, to identify genes and residues likely engaged in arms races with hosts. Bacterial genetics will then be used to functionally test evolutionary hypotheses about which genes or residues are critical for pathogen fitness. These studies will begin with the mavN gene, which appears to be engaged in an evolutionary “battle for iron” within host cells. In addition to such competitions for resources, many pathogens have evolved strategies to evade detection by host immune systems. High-throughput transposon-sequencing approaches will be used to identify bacterial genes that are required for fitness within Dictyostelium amoebae, particularly those that interact with amoeba immunity. These experiments will reveal which Legionella proteins have experienced strong selective pressures in amoeba hosts. Aim 2 will examine the host genes likely to place strong selective pressures on Legionella through studies of amoeba immune defenses. The Dictyostelium TirA protein is related to Toll-like receptors in animals, and helps the amoebae to resist Legionella infection. However, beyond these basic facts, almost nothing is known about amoeba immunity. This aim will further characterize the activity of the TirA immune pathway, identifying additional members of the immune pathway and transcriptional targets. Evolutionary and unbiased genetic approaches will highlight additional arms of the amoeba immune response that respond to Legionella infection. The proposal will combine the applicant's background in evolution, genetics, and host-microbe interactions with the Malik lab's expertise in evolutionary arms races. This interdisciplinary approach will also provide her new training in bacteriology and amoebal biology, to uncover how evolutionary arms races in the natural environment have armed Legionella for human infections.

项目摘要嗜肺军团菌是一种机会性细菌病原体，可引起致命的肺炎- 就像疾病虽然人类感染是这些细菌进化的“死胡同”，然而，由于它们对自身自然环境的适应，它们携带广泛的分子武库来攻击人类细胞。宿主环境变形虫在阿米巴原虫中的居留也可以保护军团菌免受抗生素和其他抗生素的侵害。努力从人造结构中消除细菌，使人类爆发永久化。揭示了军团菌利用宿主变形虫-特别是易受破坏的步骤-因此对以下方面有直接好处：人体健康这项提案将调查军团菌和变形虫之间的分子“军备竞赛” 已经形成了这种病原体的分子工具包，并解决了军团菌的具体假设，分泌的效应蛋白参与了阿米巴免疫途径的军备竞赛。实验军团菌和变形虫的易驾驭性和进化资源使其成为强大的宿主- 微生物模型系统，在那里可以测试进化创新的功能后果，包括宿主和微生物。目标1将调查军团菌如何受到这种军备竞赛的影响。进化的方法将分析这种生物巨大的分子武器库，效应子，以确定基因和残基可能从事军备竞赛与主机。细菌遗传学将成为用于功能性地测试进化假说，即哪些基因或残基对病原体至关重要健身这些研究将开始于mavN基因，它似乎参与了一场进化“战斗 “铁”在宿主细胞内。除了对资源的竞争，许多病原体已经进化逃避宿主免疫系统检测的策略。高通量转座子测序方法将被用于确定细菌基因，所需的适应性内网骨藻变形虫，特别是那些与阿米巴免疫相互作用的。这些实验将揭示哪些军团菌蛋白具有在变形虫宿主中经历了强大的选择压力。目标2将检查宿主基因可能放置通过研究阿米巴免疫防御对军团菌的强大选择压力。网骨藻TirA 蛋白质与动物体内的Toll样受体有关，有助于阿米巴抵抗军团菌感染。然而，除了这些基本事实之外，关于阿米巴免疫几乎一无所知。这一目标将进一步表征TirA免疫途径的活性，鉴定免疫途径的其他成员和转录靶点。进化和无偏见的遗传方法将突出其他武器的阿米巴对军团菌感染的免疫反应。该提案将联合收割机结合申请人的在进化，遗传学和宿主-微生物相互作用的背景与马利克实验室的专业知识，在进化军备竞赛这种跨学科的方法也将为她提供细菌学和变形虫学方面的新培训生物学，揭示自然环境中的进化军备竞赛如何为人类武装军团菌感染.