MOLECULAR BASIS OF PERSISTENT EHRLICHIA INFECTION

持续性埃里克体感染的分子基础

• 批准号: 6628006
• 负责人: XUE-JIE YU
• 金额: $ 26.08万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-02-01 至 2005-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6628006
• 关键词: Ehrlichia; bacterial genetics; bacterial proteins; dogs; ehrlichiosis; emerging infectious disease; epitope mapping; intracellular parasitism; membrane proteins; microorganism immunology; nucleic acid sequence; polymerase chain reaction; recombinant proteins; ticks

DESCRIPTION (Adapted from the Applicant's Abstract): Persistent infection has been observed for all ehrlichial species in a variety of animals and in humans. Understanding the mechanism of persistent ehrlichial infection will enable design of new therapeutic approaches to treat ehrlichial infections and vaccines to prevent the diseases. The following hypotheses are presented: 1) persistent infection is caused by antigenic variation and/or differential expression of the outer membrane protein (OMP) genes of Ehrlichia and 2) the OMPs confer immunity in the host against re-infection by the pathogen. The subject of this proposal is Ehrlichia chaffeensis which causes a newly emerging infectious disease, human monocytotropic ehrlichiosis. Persistent infection by E. chaffeensis has been documented in human and animals. A canine model will be employed to study the mechanism of this persistent infection. In specific aim 1, antigenic variation of E. chaffeensis gp120 will be analyzed in dogs infected by tick transmission. Canine blood will be obtained over a six month period, the gp120 gene will be amplified by PCR and sequenced and compared to the gene in the infecting isolate to determine the possible deletion or insertion of repeats in the gp120 gene. In addition, changes in the size and antigenicity of gp120 reisolated from infected canine blood will be examined. Specific aim 2 will entail analysis of the differential expression of the p28 multigene family. This will be accomplished by RT-PCR or epitope mapping. Aim 3 will involve testing of the protective immunity elicited in canines by immunization with recombinant OMPs, followed by challenge of immunized animals with E. chaffeensis. This will provide valuable information regarding the potential use of these antigens as subunit vaccines.

描述（改编自申请人的摘要）：持续感染已 在各种动物和人类的所有埃利希体物种中都观察到了这种现象。 了解埃利希体持续感染的机制将有助于 设计治疗埃立克体感染的新治疗方法 疫苗来预防疾病。提出以下假设：1) 持续感染是由抗原变异和/或差异引起的 埃利希体外膜蛋白（OMP）基因的表达和2） OMP 赋予宿主免疫力，防止病原体再次感染。这 该提案的主题是查菲埃里希体，它导致了新出现的 传染病，人类单核埃利希体病。持续感染者 查菲埃里希氏体已在人类和动物中得到记录。犬类模型将 用于研究这种持续感染的机制。具体来说 目标 1，将在狗中分析查菲埃里希球菌 gp120 的抗原变异 通过蜱传播感染。犬的血液将在六个月内获得 期间，gp120基因将通过PCR扩增并测序并与 感染分离株中的基因以确定可能的缺失或 在 gp120 基因中插入重复序列。此外，尺寸和尺寸的变化 将检查从受感染的犬血液中重新分离的 gp120 的抗原性。 具体目标 2 将需要分析 p28 的差异表达 多基因家族。这将通过 RT-PCR 或表位作图来完成。目标 3 将涉及对犬科动物引起的保护性免疫力的测试 用重组 OMP 进行免疫，然后对免疫动物进行攻击 与查菲埃里希菌。这将提供有关 这些抗原作为亚单位疫苗的潜在用途。