Defining global gene regulation and virulence determinants of relapsing fever spirochetes

项目总结/摘要 引起回归热的媒介传播的螺旋体通过软蜱传播给人类， 人体虱子尽管100多年前就确定了回归热的病原体， 关于其发病机理的信息很少。虽然回归热在发展中国家更常见， 在一些国家，蜱传回归热（TBRF）发生在美国的一些地区，在这些地区， 结核分枝杆菌出血热螺旋体的传播媒介是地方性的。在自然的地方性流行周期中，媒介传播的螺旋体 存在于节肢动物媒介和脊椎动物中发现的两个不同的小生境中。众所周知莱姆 疾病螺旋体必须经历全球基因表达的显著变化，以使它们适应 这两个不同的环境，以及大量的信息存在的监管网络， 控制细菌的适应性反应然而，在TBRF螺旋体中发生的相关性， 媒介介导的传播和哺乳动物感染仍不明确。我们的总体目标是扩大我们的 了解TBRF螺旋体的发病机制并鉴定毒力决定因素（例如，毒力 因子和调节成分）。我们假设TBRF 螺旋体必须感知环境温度，并利用这种刺激来控制基因的表达 对哺乳动物感染和媒介传播至关重要。在初步实验中，我们首先定义了 一种发生在猪疏螺旋体（Borrelia turiculum）中的全球温度依赖性基因反应， 在美国引起TBRF的物种，然后用这些数据建立一组基因， 在这个项目的研究过程中。目标1旨在确定顺式和反式调节 负责控制B中温度响应基因表达的元件。turiclavia。在目标2中， 我们将使用靶向诱变来扩增B中的单个温度响应基因。turiclavia和 确定感染和发病所需的细菌因子。这些目标将提供关键的知识 关于TBRF螺旋体在传播和感染过程中发生的差异基因调控， 确定细菌致病所需的毒力决定因子。这项研究符合 COBRE计划通过定义TBRF螺旋体的分子决定因素关注微生物致病机制 有助于哺乳动物宿主的适应和相互作用。调节因子和毒力因子 本项目中确定的潜在靶点代表了未来治疗干预和/或 可以开发TBRF的诊断方法。这些毒力决定因子的进一步表征将是 未来R 01赠款提案的重点。

PROJECT SUMMARY/ABSTRACT The vector-borne spirochetes that cause relapsing fever are transmitted to humans by either soft ticks or human body lice. Despite identification of the etiological agents of relapsing fever over 100 years ago, very little information exists regarding their pathogenesis. Although relapsing fever is more common in developing countries, tick-borne relapsing fever (TBRF) occurs in areas of the U.S. where Ornithodoros species of soft ticks, the vectors for TBRF spirochetes, are endemic. During their natural enzootic cycle, vector-borne spirochetes exist in two distinct niches found within the arthropod vector and the vertebrate. It is well established that Lyme disease spirochetes must undergo significant changes in global gene expression to allow them to adapt to these two diverse environments, and a great deal of information exists regarding the regulatory networks that control this bacterial adaptive response. However, the correlate that occurs in TBRF spirochetes to facilitate vector-mediated transmission and mammalian infection remains undefined. Our overall goal is to expand our knowledge of the pathogenesis of TBRF spirochetes and to identify virulence determinants (e.g., virulence factors and regulatory components) required during mammalian infection. We hypothesize that TBRF spirochetes must sense environmental temperature and utilize this stimulus to control expression of genes essential for mammalian infection and vector transmission. In preliminary experiments, we first defined the global temperature-dependent gene response that occurs in Borrelia turicatae, one of the major Borrelia species responsible for TBRF in the U.S., and then used these data to establish a set of genes that will be characterized during the course of studies in this project. Aim 1 seeks to identify cis- and trans-regulatory elements responsible for controlling the expression of temperature-responsive genes in B. turicatae. In Aim 2, we will use targeted mutagenesis to inactivate individual temperature-responsive genes in B. turicatae and identify bacterial factors required for infection and pathogenesis. These aims will provide critical knowledge regarding differential gene regulation occurring in TBRF spirochetes during transmission and infection, and identify virulence determinants required by the bacteria to cause disease. This research is aligned with the COBRE program's focus on microbial pathogenesis by defining molecular determinants of TBRF spirochetes that contribute to adaptation and interaction within the mammalian host. Regulators and virulence factors identified in this project represent potential targets against which future therapeutic interventions and/or diagnostics for TBRF could be developed. The further characterization of these virulence determinants will be the focus of future R01 grant proposals.