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

• 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
• 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

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.

项目摘要： 莱姆病（LD）是北半球最常见的媒介传播疾病。该疾病是引起的 由Spirochete Borrelia burgdorferi sensu lato（BBSL），从tick咬向皮肤到不同 组织，导致关节炎，心脏炎和神经性脂肪性病。目前没有有效的预防。我们的目标 是了解保护免疫的机制，以开发安全有潜在的预防工具反对 人ld。补体是血液中重要的先天防御机制，可以由多个触发 包括经典途径的途径，该途径是由抗体 - 抗原复合物诱导的，替代方案 途径是由完成C3B蛋白与微生物表面的结合触发的。这 完成的激活导致细菌表面上的孔形成C5B-9，导致裂解。在 缺乏病原体，补体调节剂抑制完成，以避免宿主细胞损伤。为了 例如，因子H（FH）特异性抑制了替代途径。螺旋体产生外表面 蛋白质，CSPZ，广泛存在于BBSL物种中，可以有效地传播给哺乳动物宿主。 CSPZ是 当细菌进入这些宿主并通过将FH招募到表面促进BBSL传播时产生 抑制完成介导的杀戮。但是，CSPZ的免疫都不影响很大的水平 杀菌抗体也不保护小鼠免受BBSL定殖。一种可能性是CSPZ受到保护 表位被FH饱和，FH不允许该蛋白诱导足够的抗体有效 消除体内BBSL。因此，我们产生了CSPZ-Y207A/Y211A突变体（CSPZ-YA），该突变体缺乏FH结合， 导致在该蛋白质的FH结合位点暴露于表位。我们发现CSPZ-YA，但没有CSPZ 疫苗接种可通过tick感染保护小鼠免受BBSL定殖。我们证明了被动免疫 CSPZ-YA-但不能CSPZ免疫的小鼠的抗体可保护小鼠免受BBSL定殖。我们 观察到前者但后来的抗体阻断了FH与CSPZ结合的结合。这些发现表明CSPZ- YA的FH结合部位暴露了，这可能会诱导保护性抗体以促进BBSL清除。那， 总体目的是定义CSPZ-YA疫苗的受保护机制。我们假设 来自CSPZ-YA疫苗接种块FH依赖性途径的保护性抗体， 促进经典途径的激活，导致BBSL杀戮。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的激活中的作用 补体途径，2）定义CSPZ-YA诱导的抗体的机制，导致BBSL清除率。 这些研究将阐明允许CSPZ-YA充当有效疫苗的机制。这样的 机制将建立基础，以进一步识别该抗原的受保护表位以识别有效 单克隆抗体作为LD预防剂。总体而言，这些信息最终将提供有效 防止BBSL感染并减少人类LD燃烧的策略。