Tick Midgut Proteins Critical for Borrelia Transmission

描述（由申请人提供）：肩周炎蜱传播伯氏疏螺旋体（莱姆病病原体）、嗜吞噬细胞无形体（人粒细胞埃利希体病病原体）和微小巴贝斯虫（人巴贝斯虫病病原体）等病原体。嗜吞噬芽胞杆菌和微小芽胞杆菌感染蜱虫的唾液腺，因此在吸血过程中随时离开蜱虫媒介。另一方面，伯氏疏螺旋体定植于蜱的中肠，通过涉及蜱的中肠蛋白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。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。虽然人们对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伯氏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。已知伯氏疏螺旋体在其生命周期中与蜱虫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预计在传播中发挥作用，但本提案将重点关注螺旋体和蜱虫中肠之间的蛋白质相互作用。我们推测伯氏疏螺旋体可能与肩胛螺旋体中肠蛋白相互作用，促进其生长和从中肠迁移；这些蜱虫蛋白可能提供新的目标来阻止莱姆病病原体的传播。为了测试这一假设，我们将利用酵母展示方法来定义蜱虫中肠蛋白，这些蛋白专门与螺旋体相互作用。RNA干扰技术将被用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。这些事件包括伯氏疏螺旋体的复制、存活、从中肠排出、通过血管迁移和进入唾液腺。不同研究小组的研究表明，在螺旋体在蜱虫中肠生长的过程中，伯氏疏螺旋体的蛋白质组发生了巨大的变化，这些变化可能受到蜱虫中肠温度、pH值或其他尚未确定的因素的影响。在这个提议中，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表达。这些研究将为蜱虫和螺旋体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为解决其他具有高度公共卫生重要性的疾病模型中的媒介-病原体和宿主-病原体相互作用提供有力工具。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。肩胛骨蜱传播伯氏疏螺旋体，莱姆病的病原体和其他病原体。在本研究中，我们将鉴定在螺旋体生长和迁移过程中与疏螺旋体相互作用的蜱中肠蛋白，并研究这种相互作用对蜱体内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.