Defining global gene regulation and virulence determinants of relapsing fever spirochetes

项目摘要/摘要 引起回归热的媒介传播的螺旋体通过软体或扁虱传播给人类 人体虱子。尽管100多年前已经确定了复发发烧的病原体，但非常 关于它们的发病机制，目前知之甚少。尽管复发热在发展中更常见 在一些国家，硬虱传播的复发热(TBRF)发生在美国的地区，那里有软蜱的鸟形目物种， TBRF螺旋体的媒介是地方性的。在其自然的地方性循环中，媒介传播的螺旋体 存在于节肢动物媒介和脊椎动物中的两个不同的生态位中。众所周知，莱姆 疾病螺旋体必须经历全球基因表达的重大变化，才能使它们适应 这两个不同的环境，以及关于监管网络的大量信息 控制这种细菌的适应性反应。然而，发生在TBRF螺旋体中的相关性有助于 媒介传播和哺乳动物感染仍未确定。我们的总体目标是扩大我们的 了解TBRF螺旋体的致病机制，并确定毒力决定因素(例如，毒力 因素和调节成分)在哺乳动物感染过程中所需。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 对于哺乳动物感染和媒介传播是必不可少的。在初步实验中，我们首先定义了 主要疏螺旋体之一的全球温度依赖性基因反应 然后利用这些数据建立了一组基因，这些基因将是 在这个项目的研究过程中表现出来的特点。目标1试图确定顺式和跨式监管 控制温度反应基因在斑潜蝇中表达的元件。在目标2中， 我们将使用定向突变来灭活白僵菌和白僵菌中的个别温度反应基因。 确定感染和致病所需的细菌因素。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的差异基因调控，以及 确定致病细菌所需的毒力决定因素。这项研究与 Cobre计划通过定义TBRF螺旋体的分子决定因素来关注微生物的发病机制 这有助于哺乳动物宿主内的适应和相互作用。调节器和毒力因子 本项目中确定的潜在目标是未来的治疗干预和/或 可以开发针对TBRF的诊断方法。这些毒力决定因素的进一步特征将是 未来R01拨款提案的重点。

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.