Surface Lipoproteins and Serum Resistance in Borrelia burgdorferi

伯氏疏螺旋体的表面脂蛋白和血清耐药性

• 批准号: 8075005
• 负责人: DARRIN R. AKINS
• 金额: $ 18.14万
• 依托单位: UNIVERSITY OF OKLAHOMA HLTH SCIENCES CTR
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-24 至 2013-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8075005
• 关键词: Bacteria; Binding; Binding Proteins; Blood; Borrelia; Borrelia burgdorferi; Borrelia burgdorferi OspE protein; C3bi; Cell surface; Collaborations; Complement; Complement 3b; Complement Factor H; Complement Inactivators; Congenital neurologic anomalies; Data; Disease; Environment; Family; Generations; Genes; Heart; Immunologic Surveillance; In Vitro; Infection; Joints; Laboratories; Lead; Lipoproteins; Lyme Disease; Mammals; Mediating; Midgut; Mus; Mutate; Neuraxis; Open Reading Frames; Order Spirochaetales; Organism; Pathogenesis; Play; Proteins; Public Health; Reporting; Resistance; Role; Serum; Skin; Suggestion; Surface; System; Therapeutic; Tick-Borne Infections; Ticks; Tissues; United States; Virulence; Virulent; base; cytotoxic; enzootic; in vivo; insight; interest; killings; mouse model; mutant; novel; novel vaccines; outer surface lipoprotein; public health relevance; transmission process

DESCRIPTION (provided by applicant): Lyme disease is caused by spirochetes that have been grouped into three different genospecies, Borrelia burgdorferi, B. afzelii, and B. garinii. Interestingly, all three genospecies seem to populate different niches in the mammalian host during infection. For example, B. burgdorferi and B. afzelii are commonly associated with disease involving the heart, joints, and skin, while B. garinii often causes central nervous system abnormalities. It was recently shown that both B. burgdorferi and B. afzelii bind host serum complement inhibitor factor H on their cell surface, which possibly enhances their resistance to serum. By contrast, most B. garinii isolates do not bind factor H and are killed by mammalian serum. This observation has led to the suggestion that B. garinii organisms persistently infect the central nervous system because it is an environment limited in cytotoxic complement. Recently, several B. burgdorferi outer surface lipoproteins (Osp) were identified by us and others that can bind factor H in vitro. The factor H binding proteins that are most relevant include a family of lipoproteins related to OspE as well as a borrelial surface lipoprotein designated CspA. Consistent with their ability to bind factor H, all of these surface lipoproteins have been shown to enhance serum resistance. We and others have previously reported that expressing the B. burgdorferi strain 297 OspE protein in a serum sensitive B. garinii strain results in increased resistance to serum-mediated killing. We also have shown that mutating the cspA gene in a virulent strain of B. burgdorferi results in a mutant that is exquisitely sensitive to serum-mediated killing. Furthermore, we also have recently shown that CspA expression is required for B. burgdorferi to survive in the midgut of ticks as they engorge on mammalian blood. The combined observations are consistent with our hypothesis that CspA and the OspE surface lipoproteins are integral to serum resistance in B. burgdorferi. To directly examine this underlying hypothesis and further examine the mechanistic role played by these proteins in transmission of B. burgdorferi from the tick to mammal, we propose the following two Specific Aims. In Specific Aim 1 we will use several novel strains we recently generated to examine the role of CspA in virulence and disease pathogenesis using the mouse model of Lyme disease. In Specific Aim 2 we will examine a strain that lacks expression of the OspE-related lipoproteins in both wild type B. burgdorferi and in our CspA mutant strain to better assess their role(s) in serum resistance and Lyme disease pathogenesis during the borrelial enzootic cycle. Finally, in the revised proposal we have included more mechanism-based studies to determine if factor H binding to CspA and OspE actually enhances degradation of C3b to iC3b on the surface of this organism, which is the current dogma in the field. Since our last submission, we have generated interesting data indicating that factor H binding proteins may not enhance generation of iC3b on the surface of B. burgdorferi after all, and we will examine this observation in more detail in our revised Aim 2. PUBLIC HEALTH RELEVANCE: The combined studies could result in the identification of new mechanisms that allow Lyme disease bacteria to evade the initial host immune surveillance system after infection. Information derived from the proposed studies could be used to generate a new vaccine or disease modulating therapeutic for Lyme disease. Given that Lyme disease is the most prevalent tick-borne infection in the United States, unique insight from the proposed studies that could lead to a new vaccine strategy for Lyme disease could greatly benefit overall public health in the United States and abroad.

描述（由申请人提供）：莱姆病是由螺旋体引起的，这些螺旋体已分为三种不同的基因种类，即Borrelia Burgdorferi，B。Afzelii和B. Garinii。有趣的是，在感染期间，这三个基因种似乎都在哺乳动物宿主中占据了不同的壁ni。例如，伯格多菲尔（B. bulgdorferi）和afzelii杂志通常与涉及心脏，关节和皮肤的疾病有关，而B. garinii通常会引起中枢神经系统异常。最近显示，B. burgdorferi和B. afzelii均在其细胞表面结合宿主血清补体抑制剂因子H，这可能会增强其对血清的抗性。相比之下，大多数Garinii分离株不结合H，并且被哺乳动物血清杀死。这一观察结果导致了以下建议：garinii生物体持续感染中枢神经系统，因为它是一个受细胞毒性补体的环境。最近，美国和其他可以在体外结合H的爆发芽孢杆菌外表面脂蛋白（OSP）。最相关的因子H结合蛋白包括与OSPE以及指定CSPA相关的脂蛋白家族。与它们结合因子H的能力一致，所有这些表面脂蛋白均已证明可增强血清耐药性。我们和其他人先前已经报道说，在血清敏感的B. garinii菌株中表达B. burgdorferi菌株297 OSPE蛋白会导致对血清介导的杀伤的耐药性。我们还表明，在B. burgdorferi毒性菌株中突变CSPA基因会导致突变体对血清介导的杀伤非常敏感。此外，我们最近还表明，B. burgdorferi需要在tick虫中生存，因为它们在哺乳动物的血液中生存。合并的观察结果与我们的假设一致，即CSPA和OSPE表面脂蛋白在B. burgdorferi中是血清耐药性不可或缺的。为了直接检查这一基本假设，并进一步研究了这些蛋白质在从乳房到哺乳动物的传播中所起的机械作用，我们提出了以下两个特定目标。在特定目的1中，我们将使用最近生成的几种新型菌株来检查CSPA使用莱姆病小鼠模型在毒力和疾病发病机理中的作用。在特定目标2中，我们将检查一种缺乏野生型B. burgdorferi和我们的CSPA突变体菌株中OSPE相关脂蛋白表达的菌株，以更好地评估其在童恋周期中血清耐药性和莱姆病发病机理中的作用。最后，在修订的建议中，我们包括了更多基于机制的研究，以确定因子H与CSPA的结合是否与CSPA结合实际上会增强C3B与IC3B在该生物体表面的降解，即该生物的表面，这是当前的田间教条。自上次提交以来，我们生成了有趣的数据，表明因子H结合蛋白可能不会增强B. burgdorferi表面上的IC3b的产生，我们将在我们的修订的AIM 2中更详细地研究了这一观察结果。 公共卫生相关性：合并的研究可能导致鉴定新机制，这些机制使莱姆病细菌能够在感染后逃避最初的宿主免疫监测系统。从拟议的研究中得出的信息可用于生成新的疫苗或疾病，调节莱姆病治疗。鉴于莱姆病是美国最普遍的tick传播感染，因此拟议的研究的独特见解可能导致新的莱姆病疫苗战略可以极大地使美国和国外的整体公共卫生受益。