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：
10392755
负责人：
Tera Catherine Levin
金额：
$ 1.41万
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 2022-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10392755
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.

项目摘要肺炎军团菌是一种机会性细菌病原体，可导致致命的肺炎爆发喜欢疾病。尽管人类感染是这些细菌的进化“死胡同”，但军团菌然而，由于其自然的适应主持人，环境变形虫。 Amoebae的住所还保护军团菌免受抗生素和其他从人造结构中消除细菌的努力，使人类爆发永存。揭示如何军团explosits主持人变形虫（尤其是步骤易于破坏），因此有直接的好处人类健康。该提议将调查军团菌和变形虫之间的分子“武器”如何已经塑造了该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具有变形虫免疫途径的武器种族。实验可用于军团菌和变形虫的障碍性和进化资源使其成为强大的宿主 - 微生物模型系统，可以在其中测试进化创新的功能后果主机和微生物。 AIM 1将调查该军备竞赛如何影响军团菌。进化方法将分析该生物的巨大分子武器（IV型）效应子，识别可能与宿主一起参加武器比赛的基因并保留基因。细菌遗传学将是用于在功能上检验哪些基因或残差对于病原体至关重要的进化假设健康。这些研究将从MAVN基因开始，MAVN基因似乎参与进化的“战斗” 对于宿主细胞内的铁。通过宿主免疫系统逃避检测的策略。高通量转座子测序方法将用于鉴定柱状脉冲中适应性所需的细菌基因，特别是那些与变形虫免疫相互作用的人。这些实验将揭示哪些军团蛋白具有 Amoeba主持人经历了强烈的选择压力。 AIM 2将检查可能放置的宿主基因通过研究变形虫免疫防御能力对军团菌的强烈选择压力。 dictyostelium tira 蛋白质与动物中的Toll样受体有关，并有助于抗变形虫抵抗军团菌感染。但是，除了这些基本事实之外，几乎没有关于变形虫免疫的了解。这个目标将进一步表征TIRA免疫途径的活性，识别免疫途径的其他成员和转录目标。进化和公正的遗传方法将突出显示的其他臂对军团菌感染反应的变形虫免疫反应。该提案将结合申请人的演变，遗传学和宿主 - 微生物与Malik Lab的进化专业知识的背景军备竞赛。这种跨学科的方法还将为她的细菌和变形虫提供新的培训生物学，以发现自然环境中的进化武器种族如何为人类武装军团感染。