Virulence and Adaptation to the Host Environment of Pathogenic Leptospira

摘要：巴斯德研究所项目2 钩端螺旋体是一个高度异质性的细菌属，钩端螺旋体是普遍存在的细菌， 环境水和土壤中的腐殖酸或病原体，可引起传播性感染， 在大鼠中无症状的携带导致人和动物的致命急性感染。尽管最近取得了进展， 钩端螺旋体属仍然研究不足，对病原体适应宿主的能力知之甚少 导致疾病在传播过程中，病原体必须绕过宿主的防御机制， 不同形式的压力。本计划项目中提出的工作旨在识别和表征细菌 促进哺乳动物宿主适应并使钩端螺旋体能够建立急性感染的决定因素。在Aim中 1，我们将确定疾病严重程度的细菌标志物。钩端螺旋体的基因组测序 我们收集的菌株和项目4（杜克）收集的临床分离株将揭示关于多样性的新见解 菌株和物种及其致病性。我们将进行首次钩端螺旋体属内大规模 进化研究，以确定逐步祖先事件在不同的进化节点，有激烈的 对我们今天所知的病原体的影响，并了解它们的贡献 生态位的适应和增强的致病性的一些物种。我们将特别 把我们的注意力集中在分离感染物种的致病亚支P1的进化节点上， 人类（P1 hv）来自未描述为人类病原体的种属（P1 lv）。假定的毒力因子将是 通过靶向诱变或基因沉默在代表性菌株中失活，或者突变体将选自 我们的随机转座子突变体库我们将与科伯恩和哈克实验室合作， 突变体的表型。我们将对项目4（杜克）采集的样本进行诊断，并提供 为实地研究提供技术支持。我们的工作还应有助于鉴定新的抗原和/或 这些标志物用于开发诊断这种被忽视的新兴疾病的新策略。目标2将 表征适应宿主环境的基因表达调节。成功的宿主定殖 需要对变化的条件进行感知和反应。双RNA-seq方法在 急性仓鼠模型将揭示L.提问者和他的主人。 对钩端螺旋体菌株在体内和不同体外条件下的转录组进行分析将增强我们的 了解病原体如何适应宿主环境以及转录因子在宿主中的作用， 调节因子如过氧化物应激调节因子PerRA和PerRB以及全局基因中的非编码小RNA 表情我们还将研究表观遗传修饰在全球基因调控和毒力中的作用， 钩端螺旋体这个项目将增加我们对这种威胁生命的病原体的生物学的理解， 钩端螺旋体病知识的许多空白，最终目标是确定 致病性钩端螺旋体感染并适应宿主。

Abstract: Project 2, Institut Pasteur Leptospira is a highly heterogeneous bacterial genus and leptospires are ubiquitous bacteria found as free-living saprophytes in environmental water and soil or as pathogens that can cause disseminated infections, from asymptomatic carriage in rats to lethal acute infection in both humans and animals. Despite recent progress, the genus Leptospira remains understudied, and little is known about the ability of the pathogen to adapt to the host and cause disease. During dissemination, pathogens must circumvent host defense mechanisms and adapt to different forms of stresses. The work proposed in this program project seeks to identify and characterize bacterial determinants that promote mammalian host adaptation and enable leptospires to establish acute infection. In Aim 1, we will identify bacterial markers of disease severity. Genome sequencing of well-characterized Leptospira strains from our collection and clinical isolates collected in project 4 (Duke) will reveal new insights on the diversity of strains and species and their pathogenicity. We will perform the first Leptospira intra-genus large-scale evolutionary study to identify stepwise ancestral events at different nodes of evolution that have drastic consequences on the pathogens as we know them today and understand what could have been their contribution to the ecological niche adaptation and enhanced virulence of some of the pathogenic species. We will particularly focus our attention on the node of evolution in the pathogenic subclade P1 that separated the species infecting humans (P1hv) from the species not described as human pathogens (P1lv). The putative virulence factors will be inactivated in representative strains by targeted mutagenesis or gene silencing, or mutants will be selected from our library of random transposon mutants. We will collaborate with the Coburn and Haake labs to assess phenotypes of mutants. We will perform diagnosis for samples collected from project 4 (Duke) and we will provide technical support for field studies. Our work should also contribute to the identification of new antigens and/or markers for the development of novel strategies for the diagnosis of this neglected emerging disease. Aim 2 will characterize the regulation of gene expression in adaptation to the host environment. Successful host colonization by Leptospira requires sensing and response to face of changing conditions. A Dual RNA-seq approach in the acute hamster model will reveal the molecular mechanisms of interactions between L. interrogans and its host. Analysis of the transcriptome of Leptospira strains in vivo and different in vitro conditions will enhance our knowledge of how the pathogen can adapt to the host environment and the roles played by transcriptional regulators such as the Peroxide Stress Regulators PerRA and PerRB and non-coding small RNA in global gene expression. We will also investigate the role of epigenetic modification in global gene regulation and virulence in Leptospira. This project will increase our understanding of the biology of this life-threatening pathogen to fill out the many gaps in leptospirosis knowledge with the ultimate goal of identifying the mechanisms by which pathogenic Leptospira infect and adapt the host.