Virulence-associated genes in the Lyme disease spirochete

摘要 伯氏疏螺旋体是莱姆病的病原体，通过复杂的生活史维持在自然界中。 涉及节肢动物(扁虱)媒介和小型哺乳动物。在扁虱和哺乳动物之间的循环中，Bb 经历了戏剧性的适应性变化，以便与这两个不同的利基市场互动和适应。一个 大量研究表明，rpoN-rpos调控通路(又称σ54-σS级联) 在BB的寄主适应和毒力基因表达中起着核心作用。具体地说，这条途径控制着 与毒力相关的主要外膜脂蛋白包括OspC、DbpA和DbpB的表达。 最近，我们发现，除了细菌增强子结合蛋白RRP2外，还有一种名为Fur/PerR的同源物 BosR也是激活RpoN-rpos途径所必需的。更重要的是，一大群 有证据表明，BosR/RpoN/rpos网络调控额外效应蛋白的表达 与BB的适合性、生存和发病机制有关。我们进行了全球转录组分析，使用 微阵列和RNA-SEQ，并且已经确定了潜在的受BosR/RpoN/rpoS调控的基因(除了OspC， DbpA和DbpB)。然而，人们对这些基因的功能和贡献几乎一无所知。 与扁虱-哺乳动物感染Bb的生命周期有关。在这项提案中，我们将直接审查两个 Bb寄生策略中的BosR/RpoN/rpos调控基因。在具体目标1中，我们将系统地 研究BB原生扁虱和哺乳动物环境中的基因表达，这将准确地确定潜在的生命- 基因靶标的特定周期作用。在具体目标2中，我们将定义这些基因在细菌中的作用 通过遗传突变方法和莱姆型疏螺旋体病小鼠模型系统的致病机制。 实现这一建议的两个具体目标将促进我们对毒力表达的理解 在BB中进行控制，并导致识别新的毒力因子。定义以下方面的贡献 BosR/RpoN/rpos调控基因对仔猪生理和发病的影响及其机制细节 在各自的基因功能下，将是我们未来研究的重点，这最终可能导致 开发预防和/或治疗莱姆病的新策略。

Abstract Borrelia burgdorferi (Bb), the etiological agent of Lyme disease, maintains itself in nature via a complex life cycle involving an arthropod (tick) vector and small mammals. During its cycle between ticks and mammals, Bb undergoes dramatic adaptive changes in order to interact with and adapt to these two disparate niches. A substantial number of studies have indicated that the RpoN-RpoS regulatory pathway (aka the σ54-σS cascade) plays a central role in host adaptation and virulence gene expression in Bb. Specifically, this pathway controls expression of major virulence-associated outer membrane lipoproteins including OspC, DbpA, and DbpB. Recently, we found that, in addition to the bacterial enhancer binding protein Rrp2, a Fur/PerR homologue called BosR is also required for the activation of the RpoN-RpoS pathway. More importantly, an overwhelming body of evidence supports that the BosR/RpoN/RpoS network governs expression of additional effector proteins associated with Bb fitness, survival, and pathogenesis. We performed global transcriptome profiling using microarray and RNA-seq and have identified potential BosR/RpoN/RpoS-regulated genes (other than ospC, dbpA and dbpB). However, virtually nothing is known regarding the functions and contributions of these genes to the tick-mammal infectious life cycle of Bb. In this proposal, we will directly examine the impact of two BosR/RpoN/RpoS-regulated genes on Bb's parasitic strategies. In Specific Aim 1, we shall systematically examine gene expression in Bb's native tick and mammal environments, which will pinpoint the potential life- cycle-specific roles of the gene targets. In Specific Aim 2, we shall define the roles of these genes in bacterial pathogenesis via genetic mutagenesis approaches and a Lyme borreliosis tick-mouse model system. Accomplishing the two Specific Aims of this proposal will advance our understanding of virulence expression control in Bb, and lead to the identification of new virulence factors. Defining the contributions of BosR/RpoN/RpoS-regulated genes to borrelial physiology and pathogenesis, and the mechanistic details underlying the respective gene functions, will be the focus of our future research, which may ultimately lead to the development of new strategies to prevent and/or treat Lyme disease.