Structure-Function of Borrelia Surface Lipoproteins

疏螺旋体表面脂蛋白的结构-功能

基本信息

批准号：
7061554
负责人：
WOLFRAM R ZUECKERT
金额：
$ 7.35万
依托单位：
UNIVERSITY OF KANSAS MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2004
资助国家：
美国
起止时间：
2004-04-15 至 2007-03-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Borrelia spirochetes causing relapsing fever (RF) can persist in an infected host by antigenic variation of Vsps and Vlps, two families of variable, immunodominant and thus serotype-defining surface lipoproteins. Vsps and Vlps induce a T-independent neutralizing IgM response, which leads to complement-independent elimination of that specific serotype. Yet, these antibodies do not protect from subsequent spirochetemia of other serotypes. Highlighting an additional evasion strategy, one of two Vsps with different binding affinities to glycosaminoglycans (GAGs) has been implicated in targeting RF Borrelia to the central nervous system, an immunopriviledged site. The overall objective of this proposal is to gain an in-depth understanding of these pathogenic processes by defining the structural and functional basis of Vsp- and VIp-mediated immune evasion and tissue tropism. Their demonstrated overlapping role in both mechanisms lead us to initially focus on the Vsps. Our preliminary data indicate that Vsps share a conserved dimeric and alpha-helical structural fold, with hypervariable loops connecting the alpha helices. We hypothesize that these variable and membrane-distal loops (i) form the Vsp-specific antibody epitopes, and (ii) also confer the surface properties involved in tissue localization. To significantly facilitate our studies, we have developed a novel surface display system, which allows us to stably express and present functional Vsps and Vlps on the surface of the Lyme disease (LD) spirochete Borrelia burgdorferi. We will now apply this system to test our hypothesis and have formulated two major specific aims: 1. to define the neutralizing antibody epitopes of Vsp proteins: Based on the three-dimensional structure of two Vsps and using specific IgG and newly generated IgM monoclonal antibodies, we will map antibody epitopes by analyzing Vsp escape mutants and antibody interactions with Vsp chimeras and point mutants. 2. to define the Vsp domains interacting with GAGs: Chimeras and point mutants of two Vsps will be examined for binding to purified GAGs, glial and endothelial cells as well as for neurotropic characteristics. These studies will significantly increase our understanding of the pathogenesis of Borrelia infections, and shed more light on the mechanisms of antigenic variation and immune evasion of microbes in general. Furthermore, they will yield important clues for the design of future intervention strategies.

描述（由申请人提供）：引起复发发烧（RF）的浮力石螺旋体可以通过VSP和VLP的抗原变异感染的宿主持续存在，这是两个可变，免疫降低的家族，因此是血清型的表面脂蛋白。 VSP和VLP诱导了T不依赖于T的中和IgM响应，从而导致与该特定血清型无关的消除。然而，这些抗体不能保护其他血清型的随后的螺旋藻。强调了一种额外的逃避策略，这是两个与糖胺聚糖（GAG）具有不同结合亲和力的VSP之一，这与将RF Borrelia靶向中枢神经系统（一种免疫保护部位）有关。该提案的总体目的是通过定义VSP和VIP介导的免疫逃避和组织性的结构和功能基础来深入了解这些致病过程。他们在这两种机制中表现出的重叠作用使我们最初专注于VSP。我们的初步数据表明，VSP共享一个保守的二聚体和α-螺旋结构折叠，而高变量环连接了α螺旋。我们假设这些变量和膜距离环（i）形成VSP特异性抗体表位，并且（ii）还赋予了与组织定位有关的表面特性。为了显着促进我们的研究，我们开发了一种新型的表面显示系统，这使我们能够稳定地表达和呈现功能性VSP和VLP，并在莱姆病（LD）螺旋体Borrelia burgdorferi表面。现在，我们将应用该系统来检验我们的假设，并提出了两个主要的具体目的： 1。为了定义VSP蛋白的中和抗体表位：基于两个VSP的三维结构，并使用特定的IgG和新生成的IGM单克隆抗体，我们将通过分析VSP逃生突变和抗体与VSP Chimeras和Point Mutants和Point Mutants和Point Mutants和Point Mutants和抗体相互作用来绘制抗体表位。 2。为了定义与GAG相互作用的VSP结构域：将检查两个VSP的嵌合体和点突变体，以与纯化的GAG，神经胶质细胞和内皮细胞以及神经性特征结合。这些研究将显着提高我们对伯罗利感染的发病机理的理解，并更多地了解抗原变异的机制和一般来说的微生物的免疫逃避。此外，它们将为未来干预策略的设计提供重要的线索。