Tick Midgut Proteins Critical for Borrelia Transmission

描述(申请人提供)：软体硬蜱传播伯氏疏螺旋体(莱姆病的病原体)、无浆体吞噬细胞性贫血(人类粒细胞性埃立克体病的病原体)和微小巴贝斯虫(人类巴贝斯虫病的病原体)等病原体。吞噬嗜血杆菌和微小芽孢杆菌感染扁虱的唾液腺，因此在取食过程中准备离开扁虱媒介。另一方面，伯氏杆菌定植在硬体中肠，通过一种涉及硬体中肠蛋白TROSPA和螺旋体脂蛋白OspA的蛋白质-蛋白质相互作用锚定在中肠。开始进食，为螺旋体提供线索，触发细菌的活跃生长和复制，因为它准备从中肠通过血淋巴迁移到唾液腺，唾液腺是脊椎动物宿主的出口。虽然人们对扁虱唾液腺转录组及其对病原体传播的动态影响的了解越来越多，但对中肠蛋白质组以及疏螺旋体在生长和迁移的关键阶段如何与中肠蛋白质相互作用的了解很少。众所周知，疏螺旋体在其生命周期中与扁虱和宿主蛋白相互作用，在恶劣和多样化的环境中传播和生存。虽然关键的非蛋白质相互作用也有望在传播中发挥作用，但这项提议将重点放在螺旋体和壁虱中肠之间的蛋白质相互作用上。我们推测，伯氏杆菌可能与我肩部中肠蛋白相互作用，以促进其生长和从中肠迁移；这些壁虱蛋白可能为阻断莱姆病病原体的传播提供新的靶点。为了测试这一假设，我们将利用酵母展示方法来定义与螺旋体特异相互作用的扁虱中肠蛋白。将利用RNA干扰技术来确定这种相互作用是否促进了传播到脊椎动物宿主之前的事件。这些事件包括疏螺旋体复制、存活、从中肠排出、通过血腔迁徙和进入唾液腺。不同研究小组的研究表明，伯氏杆菌的蛋白质组在硬蜱中肠螺旋体的生长过程中发生了戏剧性的变化，这种变化可能受到温度、pH或其他尚未确定的因素的影响。在这项提案中，我们将确定螺旋体和特定中肠蛋白之间的相互作用是否会改变螺旋体基因的表达。这些研究将为扁虱和螺旋体之间相互作用的动力学以及这些相互作用如何影响螺旋体传播提供新的见解。这些研究完成后，还将提供一个强大的工具来解决其他具有高度公共卫生重要性的疾病模型中病媒-病原体和宿主-病原体的相互作用。重要的是，这些研究将揭示伯氏疏螺旋体基因调控的一个迄今未被探索的方面，并促进对莱姆病发病机制的更好理解。与公共卫生相关的肩部硬蜱传播伯氏疏螺旋体，莱姆病的病原体以及其他病原体。在这项建议中，我们将识别在螺旋体生长和迁移过程中与疏螺旋体相互作用的扁虱中肠蛋白，并研究这种相互作用对滴虫中的疏螺旋体生长和向小鼠宿主传播的影响。

DESCRIPTION (provided by applicant): Ixodes scapularis ticks transmit Borrelia burgdorferi (agent of Lyme disease), Anaplasma phagocytophilum (agent of human granulocytic ehrlichiosis) and Babesia microti (agent of human babesiosis) among other pathogens. A. phagocytophilum and B. microti infect the salivary glands of the tick, hence poised to exit the tick vector during feeding. On the other hand, B. burgdorferi colonizes the tick midgut, anchoring to the midgut via a protein-protein interaction involving the tick midgut protein TROSPA and the spirochete lipoprotein OspA. The commencement of feeding, provides cues to the spirochete that trigger active growth and replication of the bacterium, as it prepares to migrate from the midgut through the haemolymph to the salivary glands, the port of exit to the vertebrate host. While there is a growing understanding of the tick salivary gland transcriptome and its dynamic influence on pathogen transmission, little is known about the midgut proteome and how Borrelia interacts with the midgut proteins during the critical phase of growth and migration. Borrelia is known to interact with tick and host proteins during its life cycle to disseminate and to survive in hostile and diverse milieus. While critical non-protein interactions are also expected to play a role in transmission, this proposal will focus on protein interactions between the spirochete and tick midgut. We postulate that B. burgdorferi may interact with I. scapularis midgut proteins to facilitate its growth and migration from the midgut; and that these tick proteins may offer novel targets to block the transmission of the Lyme disease pathogen. With the goal of testing this postulate, we will utilize a yeast display approach to define tick midgut proteins that specifically interact with the spirochete. RNA interference technique will be exploited to determine if the interaction facilitates the events that precede transmission to the vertebrate host. These events include Borrelia replication, survival, egress from the midguts, migration through the haemocoel and entry into salivary glands. Research efforts by various groups have demonstrated that the proteome of B. burgdorferi undergoes dramatic changes during the process of spirochete growth in the tick midgut, changes influenced perhaps by changes in temperature, pH or other as yet undefined factors in the tick midgut. In this proposal we will define if interactions between the spirochete and specific midgut proteins signals changes in spirochete gene expression. These studies will provide new insights into the dynamics of the interaction between the tick and the spirochete and how these interactions influence spirochete transmission. These studies, when completed will also provide a powerful tool to address vector-pathogen and host-pathogen interactions in other disease models of high public health importance. Importantly, these studies will reveal a hitherto unexplored facet of gene regulation in Borrelia burgdorferi and promote a greater understanding of Lyme disease pathogenesis. PUBLIC HEALTH RELEVANCE Ixodes scapularis ticks transmit Borrelia burgdorferi, the agent of Lyme disease among other pathogens. In this proposal we will identify tick midgut proteins that interact with Borrelia during spirochete growth and migration and examine the impact of this interaction on Borrelia growth in the tick and transmission to the murine host.