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

• 批准号: 10166988
• 负责人: Tera Catherine Levin
• 金额: $ 24.9万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 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/10166988
• 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; pathogen; pathogen genome; pathogenic bacteria; pressure; prevent; programs; residence; transposon sequencing

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.

项目概要 嗜肺军团菌是一种机会性细菌病原体，可导致致命性肺炎的爆发。 尽管人类感染对于这些细菌来说是进化的“死胡同”，但军团菌。 然而，由于它们对自然的适应，它们携带了大量的分子武器来攻击人类细胞。 宿主，环境变形虫居住在变形虫中也可以保护军团菌免受抗生素和其他物质的侵害。 消除人造建筑中的细菌，揭示人类如何持续爆发细菌。 军团菌利用宿主阿米巴原虫——特别是容易受到破坏的步骤——因此对以下方面有直接好处： 该提案将研究军团菌和变形虫之间的分子“军备竞赛”。 塑造了这种病原体的分子工具包，并解决了军团菌的具体假设 分泌的效应蛋白与阿米巴免疫途径进行军备竞赛。 军团菌和变形虫的易处​​理性和进化资源使其成为强大的宿主 微生物模型系统，可以测试进化创新的功能后果 目标 1 将研究军团菌如何受到这种军备竞赛的影响。 进化方法将分析这种生物体巨大的分子武器库，即 IV 型 效应器，以确定可能与宿主进行军备竞赛的基因和残留物。 用于功能测试有关哪些基因或残基对病原体至关重要的进化假设 这些研究将从 mavN 基因开始，该基因似乎正在进行一场进化“战斗”。 除了这种对资源的竞争之外，许多病原体还进化了。 逃避宿主免疫系统检测的策略。 将用于识别阿米巴盘基网柄菌适应性所需的细菌基因，特别是 这些实验将揭示哪些军团菌蛋白与阿米巴免疫相互作用。 目标2将检查阿米巴宿主中可能遭受强烈选择压力的宿主基因。 通过对阿米巴原虫免疫防御的研究，对军团菌产生强大的选择性压力。 该蛋白与动物体内的Toll样受体有关，有助于阿米巴原虫抵抗军团菌感染。 然而，除了这些基本事实之外，人们对阿米巴免疫几乎一无所知。这一目标将进一步推进。 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其他方面。 该提案将结合申请人的针对军团菌感染的阿米巴免疫反应。 进化、遗传学和宿主微生物相互作用的背景以及马利克实验室在进化方面的专业知识 这种跨学科方法也将为她提供细菌学和变形虫方面的新训练。 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。