MOLECULAR BASIS OF PERSISTENT EHRLICHIA INFECTION

描述(改编自申请者摘要)：持续性感染 在各种动物和人类身上观察到了所有埃利希族物种的感染。 了解持续埃利希菌感染的机制将使 设计新的治疗方法来治疗埃利希菌感染和 预防疾病的疫苗。提出了以下假设：1) 持续性感染是由抗原变异和/或差异引起的 埃立克体外膜蛋白基因的表达及2) OMPS使宿主对病原体的再次感染具有免疫力。这个 这项建议的主题是查菲埃利希菌，它导致了一种新的 传染病，人类单核细胞增生性埃立克体病。持续感染 查菲埃希氏菌已经在人类和动物中被记录在案。一只狗的模型会 被用来研究这种持续感染的机制。具体而言 目的1.研究查菲埃希氏菌gp120在犬体内的抗原变异。 被壁虱传播感染的。狗的血液将在六个月内获得 期间，将通过聚合酶链式反应扩增gp120基因并进行测序，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，大小和尺寸的变化 从受感染的犬血中重新分离的gp120的抗原性将被检测。 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或表位映射来完成。目标3 将涉及到测试犬只的保护性免疫 重组OMPS免疫，免疫动物挑战 与查菲斯乳杆菌。这将提供有关 这些抗原作为亚单位疫苗的潜在用途。

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.