The roles of Anaplasma phagocytophilum surface proteins in cellular invasion

嗜吞噬细胞无形体表面蛋白在细胞侵袭中的作用

• 批准号: 8510769
• 负责人: Jason A Carlyon
• 金额: $ 36.78万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-24 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8510769
• 关键词: Anaplasma phagocytophilum; Anaplasmataceae; Antisense RNA; Bacteria; Binding; Blood Vessels; Bovine Anaplasmosis; Cell Adhesion; Cells; Disease; Endothelial Cells; Equus caballus; Event; Genes; Germ Cells; Glycoproteins; Goals; Heart; Human; Infection; Infection prevention; Intervention; Invaded; Knock-out; Leukocytes; Liver; Mammalian Cell; Mediating; Membrane Proteins; Myeloid Cells; Opportunistic Infections; Organ; Organism; Predisposition; Proteins; Receptor Cell; Research; Risk; Role; Signal Transduction; Site-Directed Mutagenesis; Staging; Ticks; Transcript; Transgenic Organisms; Work; antimicrobial; cell type; design; feeding; gene function; interest; killings; knock-down; microbial; mutant; neutrophil; novel; novel strategies; pathogen; prevent; receptor; receptor binding; response; tool; uptake

DESCRIPTION (provided by applicant): Anaplasma phagocytophilum is an obligate intracellular bacterial pathogen that invades neutrophils and endothelial cells to cause the emerging and potentially fatal infection, human granulocytic anaplasmosis (HGA). A. phagocytophilum converts its host neutrophil into a Trojan Horse that facilitates pathogen replication and dissemination. It downregulates the neutrophil antimicrobial response, thereby raising susceptibility to opportunistic infections. Thus, blocking A. phagocytophilum infection of neutrophils would potentially prevent the stage of HGA associated with pathogen dissemination and increased risk of opportunistic infections. A. phagocytophilum infects microvascular endothelial cells of heart and liver. Endothelial cells are also implicated as the initial cell typ that A. phagocytophilum infects following inoculation via tick feeding. Infected endothelial cells are capable of transferring the bacterium to neutrophils. Therefore, abrogating A. phagocytophilum invasion of endothelial cells would potentially prevent infection of major organs and initial establishment of infection. The overall goal of this project is to identify and functioally characterize A. phagocytophilum outer membrane proteins that facilitate infection. We have identified outer membrane protein A (OmpA) and Asp14 (14-kDa Ap surface protein) as the first two A. phagocytophilum proteins that are critical for invasion of both myeloid cells and endothelial cells. In Aim 1, we will identify the OmpA and Asp14 domains that mediate A. phagocytophilum uptake and determine if either protein is sufficient for invasion. In Aim 2, we will identify the host cell receptors of OmpA and Asp14. In Aim 3, we will directly assess the relevance of OmpA and Asp14 to infectivity using novel transgenic A. phagocytophilum organisms that can be induced to express antisense RNA against ompA or asp14 to knock down OmpA or Asp14 expression. Achieving our goals will provide a robust understanding of A. phagocytophilum cellular invasion and identify the first two invasin-receptor pairs for any Anaplasmataceae pathogen. It will also yield a valuable tool for assessing gene function in obligate intracellular bacteria. Lastly, our work will potentially aid the design of novel intervenion strategies that target OmpA and Asp14 to prevent HGA by blocking multiple stages of infection.

描述（由申请人提供）：嗜吞噬细胞无形体是一种专性细胞内细菌病原体，侵入中性粒细胞和内皮细胞，引起新出现的潜在致命感染，人粒细胞无形体病（HGA）。嗜吞噬细胞芽胞杆菌将宿主中性粒细胞转化为特洛伊木马，促进病原体的复制和传播。它下调中性粒细胞抗微生物反应，从而增加对机会性感染的易感性。因此，阻断嗜吞噬芽胞杆菌对中性粒细胞的感染可能会阻止与病原体传播相关的HGA阶段，并增加机会性感染的风险。嗜吞噬细胞芽胞杆菌感染心脏和肝脏微血管内皮细胞。内皮细胞也被认为是嗜吞噬单胞虫通过蜱食接种后感染的初始细胞类型。受感染的内皮细胞能够将细菌转移到中性粒细胞。因此，取消嗜吞噬芽胞杆菌对内皮细胞的侵袭可能会阻止主要器官的感染和感染的初步建立。本项目的总体目标是鉴定和功能表征促进感染的嗜吞噬细胞芽胞杆菌外膜蛋白。我们已经确定了外膜蛋白A （OmpA）和Asp14 （14-kDa Ap表面蛋白）是前两个对髓细胞和内皮细胞侵袭至关重要的吞噬细胞蛋白。在Aim 1中，我们将鉴定介导嗜吞噬细胞芽胞杆菌摄取的OmpA和Asp14结构域，并确定这两种蛋白是否足以入侵。在Aim 2中，我们将鉴定OmpA和Asp14的宿主细胞受体。在Aim 3中，我们将直接评估OmpA和Asp14与感染性的相关性，使用新的转基因嗜吞噬细胞芽胞杆菌，可以诱导其表达针对OmpA或Asp14的反义RNA，从而降低OmpA或Asp14的表达。实现我们的目标将提供对嗜吞噬细胞芽胞杆菌细胞入侵的强大理解，并确定任何无形体科病原体的前两个入侵受体对。这也将为评估专性细胞内细菌的基因功能提供一个有价值的工具。最后，我们的工作将有助于设计新的干预策略，以OmpA和Asp14为目标，通过阻断多个阶段的感染来预防HGA。