Virulence Determinants of Borrelia burgdorferi

描述（由申请方提供）：伯氏疏螺旋体是北美莱姆病的病原体，由硬蜱属蜱传播。它是一种高度侵入性的螺旋体，可引起人类和其他哺乳动物的感染和表现，持续数月至数年。该病有局限性、播散性和慢性期，B。伯氏菌似乎主要通过侵入几乎任何组织、建立长期感染和诱导炎症反应的能力而引起皮肤、神经、心血管和关节炎症状。该细菌不产生已知的毒素，其发病机制在很大程度上是未知的。使用低传代、传染性B的遗传学研究。由于极低的转化率和质粒损失，伯氏螺旋体一直是具有挑战性的;因此，迄今为止，仅研究了10个基因在哺乳动物-蜱感染循环中的重要性。在这个项目中，在一个可转化的，感染性克隆的B。利用BurgdorferiB 31系统分析1740个蛋白编码基因在C3 H/HeN小鼠和肩突硬蜱感染中的作用。在目标1中，将构建约3，600个签名标记的突变体的文库，并分析插入位点;该文库将提供给所有研究者，并将作为感染性分析和体外生长所需的最小基因含量估计的基础。在目标2中，将目标1中获得的突变体组接种至小鼠中，并在接种后2至4周分析多个器官部位是否存在微生物。感染性降低的突变体将通过质粒分析和基因互补进一步表征，以确定突变基因是否为毒力决定因子。目标3将集中于鉴定B的感染性、持久性和传播所需的基因。肩胛硬蜱中的伯氏硬蜱。本研究的结果将是对B的全面看法。本研究的目的是获得哺乳动物蜱类感染周期所需的burgdorferi基因，并将在未来几年内对这些基因的功能作用进行详细分析。莱姆病是美国最常见的节肢动物传播疾病，由螺旋形细菌伯氏疏螺旋体和相关生物引起。这些细菌由蜱传播，并导致人们长期感染，影响皮肤，神经系统，关节和心脏。因为我们对B。由于莱姆病是由伯氏菌引起的疾病，因此很难设计出更好的方法来预防、诊断和治疗莱姆病。本研究的目的是识别每一个B。莱姆病基因在感染过程中很重要，这样我们就可以利用由此产生的信息来帮助减少莱姆病对美国和世界其他地区人民的影响。

DESCRIPTION (provided by applicant): Borrelia burgdorferi is the causative agent of Lyme disease in North America and is transmitted by ticks of the genus Ixodes. It is a highly invasive spirochete that can cause infection and manifestations in humans and other mammals that persist for months to years. The disease has localized, disseminated, and chronic stages, and B. burgdorferi appears to cause dermal, neurologic, cardiovascular, and arthritic symptoms primarily though the ability to invade almost any tissue, establish long-term infection, and induce inflammatory responses. The bacterium produces no known toxins, and its mechanisms of pathogenesis are largely unknown. Genetic studies using low-passage, infectious B. burgdorferi have been challenging due to exceedingly low transformation rates and plasmid loss; as a result, only 10 genes have been investigated to date with regard to their importance in the mammal-tick infectious cycle. In this project, signature-tagged mutagenesis in a transformable, infectious clone of B. burgdorferi B31 will be used to systematically analyze the roles of the 1740 protein-encoding genes in the infection of C3H/HeN mice and Ixodes scapularis ticks. In Aim 1, a library of -3,600 signature-tagged mutants will be constructed and insertion sites analyzed; this library will be made available to all investigators and will serve as a basis for infectivity analysis and the estimation of the minimal gene content required for in vitro growth. In Aim 2, groups of the mutants obtained in Aim 1 will be inoculated into mice and multiple organ sites analyzed for the presence of organisms 2 to 4 weeks after inoculation. Mutants with decreased infectivity will be characterized further by plasmid analysis and gene complementation to determine whether the mutated genes are virulence determinants. Aim 3 will be focused on the identification of genes required for the infectivity, persistence and transmission of B. burgdorferi in Ixodes scapularis ticks. The result of this study will be a comprehensive view of the B. burgdorferi genes required for mammal-tick infectious cycle, and will fuel the detailed analysis of the functional roles of these genes in future years. Lyme disease, the most common arthropod-borne disease in the United States, is caused by the spiral-shaped bacterium Borrelia burgdorferi and related organisms. These bacteria are transmitted by ticks and cause a long-term infection in people that affects the skin, nervous system, joints, and heart. Because we know so little about how B. burgdorferi causes disease, it is difficult to design better ways to prevent, diagnose, and treat Lyme disease. The goal of this study is to identify every B. burgdorferi gene that is important in the infection process, so that we can use the resulting information to help reduce the impact of Lyme disease on people in the United States and in other parts of the world.