TYPE IV SECRETION & SIGNAL TRANSDUCTION IN EHRLICHIOSIS

性状（由申请方提供）：由查菲埃立克体引起的人单核细胞埃立克体病（HME）和由嗜吞噬细胞无形体引起的人粒细胞埃立克体病（HGE）是新发传染病。这些细菌是挑剔的专性细胞内细菌，需要在两种截然不同的宿主（脊椎动物和无脊椎动物）之间重复传播。这些细菌如何进入并继续在敌对的宿主环境（如中性粒细胞或蜱虫载体）中茁壮成长，在很大程度上是未知的。我们最近的特点是基因编码的IV型分泌系统（T4 SS）和两个组件的调节系统（2CRS）的HGE和HME代理。该提案旨在了解T4 SS和2CRS在HME和HGE发病机制中的作用。 本项目的具体目标如下：1.检测单个大肠杆菌表达的T4 SS蛋白的共定位。chaffeensis和A.嗜吞噬细胞生物与内体-溶酶体标志物和信号分子在人白细胞中的附着，内化和随后的增殖，并响应于环境刺激。 2.表征蜱传播过程中T4 SS在蜱和哺乳动物皮肤中的表达。 3.识别T4 SS效应分子或底物分子。4.对E. chaffeensis和A.通过表达重组蛋白并研究体外和体内环境条件下传感激酶和反应调节剂的磷酸化，以及通过检测2CRS（组氨酸激酶）抑制剂对E. chaffeensis和A.嗜吞噬细胞;并通过研究基因调控的2CRS。 5.构建A.嗜吞噬细胞E.其中预测的关键基因被破坏，或有条件地沉默，以确定T4 SS和2CRS的功能。本研究为了解专性胞内细菌与哺乳动物和蜱类宿主之间的动态信号传递提供了新的视角。该项目可能会在这一研究领域取得技术突破。这些结果可能为HME和HGE的新治疗和预防提供了一个潜在的靶点。

DESCRIPTION (provided by the applicant): Human monocytic ehrlichiosis (HME) caused by Ehrlichia chaffeensis and human granulocytic ehrlichiosis (HGE) caused by Anaplasma phagocytophila, are emerging infectious diseases. These bacteria are fastidious obligatory intracellular bacteria that require repeated transmission between two vastly different hosts: vertebrates and invertebrates. How these bacteria enter and continue to thrive within hostile host milieu such as neutrophils or the tick vector is largely unknown. We recently characterized genes encoding a type IV secretion system (T4SS) and two component-regulatory system (2CRS) in HGE and HME agents. This proposal aims to understand the roles of T4SS and 2CRS in pathogenesis of HME and HGE. The specific aims of this project are as follows: 1. Examine the colocalization of T4SS proteins expressed by individual E. chaffeensis and A. phagocytophila organisms with endosome-lysosome markers and signaling molecules in human leukocytes during attachment, internalization, and subsequent proliferation, and in response to environmental stimuli. 2. Characterize expression of T4SS in ticks and the skin of mammals during tick transmission. 3. Identify T4SS effector or substrate molecules. 4. Characterize the 2CRS of E. chaffeensis and A. phagocytophila by expressing recombinant proteins and studying the phosphorylation of sensor kinases and response regulators in vitro, and in vivo under controlled sets of environmental conditions; by examining the effects of 2CRS (histidine kinase) inhibitors on phenotypes of E. chaffeensis and A. phagocytophila; and by studying genes regulated by 2CRS. 5. Construct novel mutants ofA. phagocytophila and E. chaffeensis in which a predicted critical gene is disrupted, or conditionally silenced to determine the functions of T4SS and 2CRS. The data obtained from this study will provide a new perspective for understandings the dynamic signaling events between obligatory intracellular bacteria and their mammalian and tick hosts. This project will potentially provide a technical breakthrough in this field of research. The results may point to a potential target for new treatment and prevention of HME and HGE.