Transit of Borrelia burgdorferi through the Ixodes scapularis midgut proceeds in

描述（由申请人提供）：尽管我们对伯氏疏螺旋体差异基因表达的理解取得了相当大的进展，但使伯氏疏螺旋体在其节肢动物载体和哺乳动物宿主之间循环的分子相互作用和调控事件尚不清楚。本提案中提出的研究基于这样一种观念，即对受感染蜱体内的Bb进行更彻底的分析，将为螺旋体传播中涉及的毒力相关过程提供有价值的见解。我们使用GFP+菌株297分离物进行的初步研究挑战了关于Bb在摄食过程中如何从若虫中肠迁移的传统思维。在吸血过程中，Bb在壁虱中肠内作为非运动网络复制，利用中肠重塑造成的弱点进入基膜。然后，Bb经历了从非运动网络到个体运动生物体的戏剧性转变，这些生物体能够穿透MG上皮进入血液，迁移到唾液腺，并最终感染哺乳动物宿主组织。在这个应用中，我们建议使用分子、遗传和显微成像方法的组合来更精确地描述莱姆病螺旋体和它的节肢动物载体在整个摄食过程中发生的相互作用。通过完善我们对螺旋体和蜱虫因素之间相互作用的理解，我们将进一步实现我们的长期目标，以确定螺旋体，以及伊克斯德，基因产物和调控途径，促进螺旋体在蜱虫和哺乳动物中的传播。通过确定在病原体-媒介界面起作用的关键成分，我们将为开发新的治疗策略奠定基础，包括能够阻断向人类宿主传播以及在人类宿主内部传播的候选疫苗。

DESCRIPTION (provided by applicant): Despite considerable advances in our understanding of borrelial differential gene expression, the molecular interactions and regulatory events that enable Borrelia burgdorferi to cycle between its arthropod vector and mammal host are not well understood. The studies presented in this proposal are predicated on the notion that a more thorough analysis of Bb within infected ticks will provide valuable insight into the virulence-related processes involved in spirochete transmission. Our preliminary studies using a GFP+ strain 297 isolate challenge the conventional thinking of how Bb migrate out of the nymphal midgut during feeding. During the bloodmeal, Bb replicate within the tick midgut as non-motile networks, gaining access to the basement membrane by taking advantage of the weakness created by midgut remodeling. Bb then undergo a dramatic transition from the non-motile networks to individual motile organisms that are able to penetrate through the MG epithelium into the hemocoel, migrate to the salivary glands, and ultimately, infect mammalian host tissues. In this application, we propose using a combination of molecular, genetic and microscopic imaging methodologies to more precisely delineate the interactions that occur between the Lyme disease spirochete and its arthropod vector throughout the feeding process. By refining our understanding of the interplay between spirochetal and tick factors, we will further our long-term objective to identify borrelial, as well as ixodid, gene products and regulatory pathways that promote spirochete dissemination within both ticks and mammals. By identifying key components acting at the pathogen-vector interface, we will be setting the stage for the development of novel therapeutic strategies, including vaccine candidates capable of blocking transmission to, as well as dissemination within, the human host. PUBLIC HEALTH RELEVANCE: Borrelia burgdorferi (Bb), the causative agent of Lyme disease (LD), is maintained within nature by an enzootic life cycle that involves an Ixodes tick vector and a mammalian host, typically wild rodents. The studies presented in this proposal are predicated on the notion that a more thorough analysis of spirochetes within ticks will provide valuable insight into how Bb is transmitted to its reservoir host and humans. By refining our understanding of the interplay between Bb and the tick midgut epithelium, we will further our long-term objective to identify borrelial, as well as tick, gene products and regulatory pathways that promote maintenance of Bb within its tick-mouse infectious cycle.