Analysis of L. Pneumophilia Virulence Regulation

描述（由申请人提供）：微生物的一个特征是能够改变其生理以适应或利用当地条件。适应对病原体至关重要，因为这些微生物在定植和传播之间循环时面临不同的环境。作为阐明微生物分化对发病机制影响的实验模型，我们分析了一种吞噬细胞的革兰氏阴性细胞内病原体。在这里，我们验证了这样一个假设，即为了在人肺及其水生水库中茁壮成长，嗜肺乳杆菌以一种互惠的模式表达至少两套不同的生化途径：一套促进吞噬细胞液泡中的复制，另一套刺激宿主细胞之间的传播。关于其LetA/S双组分调控系统旨在赋予病原体多功能性的假设也将进行测试。通过利用控制嗜肺乳杆菌分化的调控回路的知识，缺乏调节因子FliA、LetA、LetS或CsrA或苏氨酸转运体PhtA的突变体，Philadelphia、Paris和Lens菌株的基因组序列，生物信息学和微阵列技术，以及功能的分子和遗传分析，可以阐明病原体在细胞内复制和传播之间循环的机制。对生命周期的每个阶段至关重要的分子特征可以为设计药物提供信息，以从受污染的水源和受感染的肺部中根除这种机会性病原体。总之，这些研究将为研究细胞内微生物从环境中出现并引起机会性感染的生化途径提供一个框架。因此，这里确定的概念和途径也可以指导研究和管理不易处理的细胞内病原体，如分枝杆菌、衣原体、Francisella和Coxiella物种。

DESCRIPTION (provided by applicant): A hallmark of microbes is the ability to alter their physiology to tolerate or exploit local conditions. Adaptation is crucial for pathogens, since these microorganisms confront distinct environments as they cycle between periods of colonization and transmission. As an experimental model to elucidate the impact of microbial differentiation on pathogenesis, we analyze a gram-negative intracellular pathogen of phagocytes. Here we test the hypothesis that, to thrive in the human lung and its aquatic reservoir, L. pneumophila expresses in a reciprocal pattern at least two distinct sets of biochemical pathways: one to promote replication in phagocyte vacuoles and the other to stimulate transmission between host cells. The hypothesis that its LetA/S two- component regulatory system is designed to confer versatility to the pathogen will also be tested. By exploiting knowledge of the regulatory circuit that governs L. pneumophila differentiation, mutants that lack the regulators FliA, LetA, LetS, or CsrA, or the threonine tranporter PhtA, the genome sequences of the Philadelphia, Paris and Lens strains, bioinformatic and microarray technology, and molecular and genetic assays of function, mechanisms that equip pathogens to cycle between intracellular replication and transmission can be elucidated. The molecular features critical to each stage of the life cycle can inform design of agents to eradicate this opportunistic pathogen from contaminated water supplies and from the infected lung. Together, these studies will provide a framework to investigate the biochemical pathways that equip intracellular microbes to emerge from the environment to cause opportunistic infections. Thus, concepts and pathways identified here can also guide studies and management of less tractable intracellular pathogens such as the Mycobacteria, Chlamydia, Francisella, and Coxiella species.