Study of Immune Avoidance During the Enzootic Cycle of the Lyme Disease Pathogen

项目摘要 莱姆病螺旋体（Borrelia）免疫逃避和持续感染的关键机制 burgdorferi，是VlsE表面蛋白的抗原变异。尽管存在大量的 除了存在于细菌表面的其他蛋白质外，VlsE是唯一表现出持续变异的抗原。 它的表面抗原决定基。我们实验室最近的工作已经确定了一个可能的VlsE介导的免疫逃避系统 其允许非VlsE表面抗原逃避宿主抗体的杀伤作用。尽管最近 证据表明，VlsE在调节宿主免疫系统中的作用迄今尚未被探索。此外，委员会认为， 在病原体的地方流行周期中，研究vlsE抗原变异的重要性的研究是 根本不存在我们的长期目标是确定VlsE对宿主的任何潜在调节作用 免疫反应本应用程序的目的是确定B是否逃脱。burgdorferi 来自宿主储库中免疫监视的表面抗原需要VlsE和宿主免疫分子。 基于初步发现，我们的中心假设是VlsE介导BBF 01的免疫逃避， 使用需要IgM的过程从储库宿主的抗体中分离脂蛋白。的理由 提出的研究是，确定VlsE促进的保护系统的存在和分子细节， 在B。burgdorferi将大大推进我们对这种病原体如何逃避宿主免疫的认识， 系统因此，拟议的研究与NIH的使命的一部分有关， 基础知识，这将可能有助于减少人类疾病和残疾的负担。 在初步研究结果的指导下，我们的假设将通过追求三个具体目标进行测试：1） 证明B的VlsE要求。再感染时的伯氏螺旋体表面抗原免疫回避 天然储库宿主; 2）确定BBF 01逃避宿主抗体的VlsE需求;和3） 确定在VlsE介导的免疫逃避中对IgM抗体的需求。在第一个目标下， 将用蜱衍生的突变型或野生型疏螺旋体攻击Peromyscus小鼠，以寻找其在小鼠体内表达的能力。 宿主再感染的可能性在第二个目的下，用BBF 01抗血清免疫的小鼠将用以下任一种进行攻击： 蜱来源的野生型或VlsE/BBF 01缺陷型克隆，以确定VlsE的存在是否阻止BBF 01 被宿主抗体识别最后，第三个目标将利用感染以下任一种的Rag-/-小鼠： 突变型或野生型疏螺旋体以测定VlsE介导的抗体逃避的IgM需求。的 这项工作是创新性的，因为它涉及到具有主动体液反应的储毒鼠的再感染 到B。burgdorferi为了解决VlsE促进的保护的问题，并利用各种vlsE突变体 B。用于感染蜱媒介和宿主储库的burgdorferi克隆。这种方法可能会提供 在制定预防和治疗人类莱姆病的策略方面提供更多有用的知识。

Project Summary A key mechanism for immune evasion and persistent infection by the Lyme disease spirochete, Borrelia burgdorferi, is antigenic variation of the VlsE surface protein. Despite the presence of a substantial number of additional proteins residing on the bacterial surface, VlsE is the only antigen that exhibits ongoing variation of its surface epitope. Recent work in our lab has identified a possible VlsE-mediated immune evasion system that allows non-VlsE surface antigens to escape the killing effects of host antibodies. Despite this recent evidence, a role for VlsE in modulating the host immune system has never been explored to date. Moreover, studies investigating the importance of vlsE antigenic variation during the pathogen's enzootic cycle are nonexistent. Our long-term goals are to determine any potential modulatory effects by VlsE on the host immune response. The objective of this application is to determine whether the escape of B. burgdorferi surface antigens from immune surveillance in the host reservoir requires VlsE and host immune molecules. Based on preliminary findings, our central hypothesis is that VlsE mediates immune evasion of the BBF01 lipoprotein from antibodies of the reservoir host using a process that requires IgM. The rationale for the proposed research is that identifying the presence and molecular details of a VlsE-promoted protection system in B. burgdorferi would significantly advance our knowledge how this pathogen evades with the host immune system. Thus, the proposed research is relevant to that part of NIH's mission that pertains to developing fundamental knowledge that will potentially help to reduce the burdens of human illness and disability. Guided by preliminary findings, our hypothesis will be tested by pursuing three specific aims: 1) Demonstrate a VlsE requirement for B. burgdorferi surface antigen immune avoidance during reinfection of the natural reservoir host; 2) Determine a VlsE requirement for BBF01 evasion from host antibodies; and 3) Determine a requirement for IgM antibodies in VlsE-mediated immune evasion. Under the first aim, VlsE-na¿ve Peromyscus mice will be challenged with either tick-derived mutant or wild type Borrelia to look for a capacity for host reinfection. Under the second aim, mice immunized with BBF01 antisera will be challenged with either tick-derived wild type or VlsE/BBF01-deficient clones to determine if the presence of VlsE prevents BBF01 from being recognized by host antibodies. Finally, the third aim will utilize Rag-/- mice infected with either mutant or wild type Borrelia in order to assay for an IgM requirement for VlsE-mediated antibody evasion. The proposed work is innovative, because it involves reinfection of reservoir mice with an active humoral response to B. burgdorferi in order to address the question of VlsE-promoted protection, and utilizes various vlsE mutant B. burgdorferi clones for infection of both the tick vector and host reservoir. This approach will likely provide more useful knowledge in developing strategies to prevent and treat Lyme disease in humans.