MOLECULAR BASIS OF PERSISTENT EHRLICHIA INFECTION

描述（改编自申请人摘要）：持续性感染具有 在各种动物和人类中观察到所有埃里希体物种。 了解持续性埃立克体感染的机制将使 设计治疗埃立克体感染的新治疗方法， 疫苗来预防疾病。提出了以下假设：1） 持续性感染是由抗原变异和/或差异 埃里希体属外膜蛋白（OMP）基因的表达; OMP赋予宿主免疫力以抵抗病原体的再感染。的 该提案的主题是查菲埃里希体，它引起一种新出现的 传染病，人类嗜单核细胞埃里希体病。持续感染， E.在人类和动物身上都有记录。一个狗模型将 研究这种持续性感染的机制。在特定 目的1、E.将在犬中分析查菲gp 120 被蜱虫感染将在六个月内采集犬血 在此期间，gp 120基因将通过PCR扩增并测序， 感染分离株中的基因，以确定可能的缺失，或 在gp 120基因中插入重复序列。此外，规模和 将检测从感染的犬血液中再分离的gp 120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 将涉及测试犬的保护性免疫力， 用重组OMP免疫，然后攻击免疫动物 用大肠chaffeensis。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.