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

描述（由申请方提供）：莱姆病螺旋体（伯氏疏螺旋体）的免疫逃避和持续感染的关键机制是VlsE表面蛋白的抗原变异。尽管存在大量存在于细菌表面上的额外蛋白质，但VlsE是唯一表现出其表面表位持续变化的抗原。我们实验室最近的工作已经确定了一种可能的VlsE介导的免疫逃避系统，该系统允许非VlsE表面抗原逃避宿主抗体的杀伤作用。尽管最近的证据表明，VlsE在调节宿主免疫系统中的作用迄今尚未被探索。此外，研究调查的重要性vlsE抗原变异在病原体的地方流行周期是不存在的。我们的长期目标是确定VlsE对宿主免疫应答的任何潜在调节作用。本申请的目的是确定B是否逃脱。来自宿主储库中免疫监视的伯氏螺旋体表面抗原需要VlsE和宿主免疫分子。基于初步发现，我们的中心假设是VlsE使用需要IgM的过程介导BBF 01脂蛋白从储存宿主的抗体的免疫逃避。该研究的基本原理是鉴定B中VlsE促进的保护系统的存在和分子细节。burgdorferi的发现将大大提高我们对这种病原体如何躲避宿主免疫系统的认识。因此，拟议中的研究与NIH的使命的一部分有关，该使命涉及开发可能有助于减轻人类疾病和残疾负担的基础知识。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。2）确定天然储库宿主再感染期间的伯氏螺旋体表面抗原免疫逃避; 2）确定BBF 01逃避宿主抗体的VlsE需求;和3）确定VlsE介导的免疫逃避中对IgM抗体的需求。在第一个目标下，将用蜱来源的突变体或野生型疏螺旋体攻击VlsE-幼稚的Peromyscus小鼠，以寻找宿主再感染的能力。在第二个目的下，用BBF 01抗血清免疫的小鼠将用蜱来源的野生型或VlsE/BBF 01缺陷型克隆进行攻击，以确定VlsE的存在是否阻止BBF 01被宿主抗体识别。最后，第三个目的将利用感染突变型或野生型疏螺旋体的Rag-/-小鼠，以测定VlsE介导的抗体逃避的IgM需求。这项工作是创新性的，因为它涉及到对B有积极体液反应的贮库小鼠的再感染。burgdorferi中，以解决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。 这种方法可能会为制定预防和治疗人类莱姆病的策略提供更多有用的知识。

DESCRIPTION (provided by applicant): 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-naive 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 i 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.