Identification of the mechanism of protection against a B. burgdorferi protein CspZ for the prevention of Lyme disease

鉴定伯氏疏螺旋体蛋白 CspZ 预防莱姆病的机制

基本信息

批准号：
10090562
负责人：
Maria Elena Bottazzi
金额：
$ 19.95万
依托单位：
WADSWORTH CENTER
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-02-01 至 2024-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10090562
关键词：
Accounting Affinity Chromatography Alternative Complement Pathway Antibodies Antigen-Antibody Complex Antigens Arbovirus Infections Arthritis Bacteria Binding Binding Sites Blocking Antibodies Blood Borrelia Infections Borrelia burgdorferi Borrelia burgdorferi Group Carditis Column Chromatography Complement Complement 3b Complement Activation Complement Factor H Complement Membrane Attack Complex Complex Cytolysis Defense Mechanisms Deposition Disease Epitopes Exposure to Foundations Goals Health Human Immobilization Immunity Immunization Immunize Immunoglobulin G In Vitro Infection Lead Length Lyme Disease Mediating Membrane Proteins Molecular Monoclonal Antibodies Mus Order Spirochaetales Oryctolagus cuniculus Passive Immunization Pathogenicity Pathway interactions Prevention Proteins Reporting Role Site Skin Surface Testing Therapeutic antibodies Tick-Borne Diseases Ticks Tissues United States Vaccination Vaccines Vector-transmitted infectious disease Work bactericide blocking factor cell injury improved in vivo microbial mutant pathogen prevent prophylactic recruit tick bite tool vaccine-induced antibodies

项目摘要

Project Summary: Lyme disease (LD) is the most common vector-borne disease in the northern hemisphere. The disease is caused by the spirochete Borrelia burgdorferi sensu lato (Bbsl), which spreads from a tick bite to the skin to different tissues, leading to arthritis, carditis, and neuroborreliosis. No effective prevention is currently available. Our goal is to understand the mechanisms of protective immunity to develop safe and potent prevention tools against human LD. Complement is an important innate defense mechanism in the blood that can be triggered by multiple pathways including the classical pathway, which is induced by antibody-antigen complexes, and the alternative pathway, which is triggered by the binding of the complement C3b protein with the microbial surface. The activation of complement results in a pore-forming complex, C5b-9, on the bacterial surface leading to lysis. In the absence of pathogens, complement is inhibited by complement regulators to avoid host cell damages. For example, Factor H (FH) specifically inhibits the alternative pathway. Spirochetes produce an outer surface protein, CspZ, widely present in Bbsl species that can be efficiently transmitted to mammalian hosts. CspZ is produced when bacteria enter these hosts and facilitates Bbsl dissemination by recruiting FH to its surface thus inhibiting complement-mediated killing. However, immunization of CspZ neither induces great levels of bactericidal antibodies nor does it protect mice from Bbsl colonization. One possibility is that CspZ’s protective epitopes are saturated by FH, which would not allow this protein to induce sufficient antibodies to efficiently eliminate Bbsl in vivo. We thus generated a CspZ-Y207A/Y211A mutant (CspZ-YA) that is deficient in FH-binding, leading to the exposure of the epitopes on this protein’s FH-binding sites. We found that CspZ-YA but not CspZ vaccination protects mice from Bbsl colonization via tick infection. We demonstrated that passive immunization of the antibodies from CspZ-YA- but not CspZ-immunized mice protects mice from Bbsl colonization. We observed that the former but not later antibodies block FH binding to CspZ. These findings suggest that CspZ- YA’s FH-binding site is exposed, which could induce protective antibodies to promote Bbsl clearance. Thus, the overall objective is to define the protective mechanisms of the CspZ-YA vaccine. We hypothesize that the protective antibodies from CspZ-YA vaccination block FH-dependent evasion of the alternative pathway and promote activation of the classical pathway, resulting in Bbsl killing. To test the hypothesis, we will 1) assess the role of the antibodies induced by CspZ-YA vaccination in promoting the activation of classical and alternative complement pathways, 2) define the mechanisms of the CspZ-YA-induced antibodies leading to Bbsl clearance. These studies will elucidate the mechanisms that allow CspZ-YA to function as an effective vaccine. Such mechanisms will build the foundation to further identify the protective epitopes of this antigen to identify potent monoclonal antibodies as LD prophylactic agents. Overall, this information will ultimately provide effective strategies to prevent Bbsl infection and reduce the burden of human LD.

项目概要：莱姆病（LD）是北半球最常见的媒介传播疾病。由螺旋体伯氏疏螺旋体 (Bbsl) 引起，它通过蜱虫叮咬传播到皮肤上组织，导致关节炎、心脏炎和神经疏螺旋体病，目前尚无有效的预防措施。是了解保护性免疫的机制，以开发安全有效的预防工具人类LD是血液中重要的先天防御机制，可以由多种物质触发。途径包括由抗体-抗原复合物诱导的经典途径和替代途径该途径是由补体 C3b 蛋白与微生物表面的结合触发的。补体的激活导致细菌表面形成孔形成复合物 C5b-9，从而导致裂解。在没有病原体的情况下，补体被补体调节剂抑制以避免宿主细胞损伤。例如，因子 H (FH) 特异性抑制螺旋体产生外表面。 CspZ 蛋白广泛存在于 Bbsl 物种中，可有效传播至哺乳动物宿主。当细菌进入这些宿主时产生，并通过将 FH 募集到其表面来促进 Bbsl 传播，从而抑制补体介导的杀伤然而，CspZ 的免疫既不诱导高水平的补体介导的杀伤。杀菌抗体也不能保护小鼠免受 Bbsl 定植，一种可能性是 CspZ 的保护作用。表位被 FH 饱和，这不允许该蛋白诱导足够的抗体来有效地因此，我们产生了缺乏 FH 结合的 CspZ-Y207A/Y211A 突变体 (CspZ-YA)，导致该蛋白质的 FH 结合位点上的表位暴露，我们发现 CspZ-YA 而不是 CspZ。疫苗接种可保护小鼠免受蜱虫感染引起的 Bbsl 定植。来自 CspZ-YA 而非 CspZ 免疫小鼠的抗体可以保护小鼠免受 Bbsl 定植。观察到前者而不是后者阻断 FH 与 CspZ 的结合。这些发现表明 CspZ-。 YA 的 FH 结合位点暴露，可以诱导保护性抗体促进 Bbsl 清除。总体目标是确定 CspZ-YA 疫苗的保护机制。 CspZ-YA 疫苗接种产生的保护性抗体可阻断 FH 依赖性旁路途径的逃避，促进经典途径的激活，导致 Bbsl 杀死为了检验假设，我们将 1) 评估。 CspZ-YA疫苗接种诱导的抗体在促进经典和替代激活中的作用补体途径，2) 定义了 CspZ-YA 诱导的先导抗体对 Bbsl 清除的机制。这些研究将阐明 CspZ-YA 作为有效疫苗的机制。机制将为进一步鉴定该抗原的保护性表位奠定基础，以识别有效的总的来说，这些信息最终将提供有效的 LD 预防剂。预防 Bbsl 感染和减轻人类 LD 负担的策略。