Tick Midgut Proteins Critical for Borrelia Transmission

描述（由申请方提供）：肩突硬蜱传播伯氏疏螺旋体（莱姆病病原体）、嗜吞噬细胞无形体（人粒细胞埃立克体病病原体）和小巴贝斯虫（人巴贝虫病病原体）等病原体。A.嗜吞噬细胞菌和B.田鼠感染蜱的唾液腺，因此在进食期间准备离开蜱媒介。另一方面，B。伯氏螺旋体定殖蜱中肠，通过涉及蜱中肠蛋白TROSPA和螺旋体脂蛋白OspA的蛋白质-蛋白质相互作用锚定到中肠。进食的开始为螺旋体提供了触发细菌活跃生长和复制的线索，因为它准备从中肠通过血淋巴迁移到唾液腺，这是脊椎动物宿主的出口。虽然蜱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知之甚少。已知疏螺旋体在其生命周期中与蜱和宿主蛋白相互作用以传播并在敌对和多样化的环境中生存。虽然关键的非蛋白质相互作用也有望在传播中发挥作用，但该提案将重点关注螺旋体和蜱中肠之间的蛋白质相互作用。我们假设B. burgdorferi可能与I.肩胛蜱中肠蛋白，以促进其生长和迁移的中肠;这些蜱蛋白可能提供新的目标，以阻止莱姆病病原体的传播。为了验证这一假设，我们将利用酵母展示的方法来确定蜱中肠蛋白，特异性地与螺旋体相互作用。将利用RNA干扰技术来确定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、通过血腔迁移和进入唾液腺。不同研究小组的研究成果表明，B.在蜱中肠中螺旋体生长的过程中，伯氏螺旋体经历了显著的变化，这些变化可能受到蜱中肠中温度、pH或其他尚未确定的因素的变化的影响。在这个提议中，我们将确定是否螺旋体和特定的中肠蛋白之间的相互作用的信号在螺旋体基因表达的变化。这些研究将为蜱虫和螺旋体之间的相互作用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，以解决媒介-病原体和宿主-病原体相互作用的其他疾病模型的高度公共卫生的重要性。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探索的方面，并促进对莱姆病发病机制的更深入了解。公共卫生相关性肩突硬蜱传播莱姆病病原体伯氏疏螺旋体。在这项提案中，我们将确定蜱中肠蛋白与疏螺旋体在螺旋体的生长和迁移过程中相互作用，并检查这种相互作用对疏螺旋体在蜱中的生长和向鼠宿主的传播的影响。

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.