Genetic determinants of mammalian host adaptation by the Lyme disease spirochete.

描述（由申请方提供）：伯氏疏螺旋体是一种专性寄生虫，在自然界中通过涉及蜱和哺乳动物宿主的复杂循环维持。这两种非常不同的宿主类型之间的转换需要通过基因表达的变化快速适应的能力。人工感染的研究提供了一些这些基因的信息，可能会差异表达的条件下类似的脊椎动物宿主。尽管取得了这一进展，但在我们对哺乳动物宿主适应的一些基因的作用和功能的理解方面仍然存在根本性的差距。我们的长期目标是鉴定和表征适应B所必需的蛋白质。burgdorferi的蜱和哺乳动物宿主环境。本申请的总体目标是识别B。使用小鼠模型，筛选特异性适应哺乳动物宿主所需的burgdorferi候选基因。中心假设是大量的B。自适应表达未知功能的Burgdorferi基因。此外，我们假设一些对宿主适应很重要的基因要么是瞬时表达的，要么只在小鼠感染的后期才被打开。拟议研究的基本原理是，一旦确定了适应宿主环境的基因，就有可能确定它们在建立哺乳动物感染中的各自作用。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。以出版的B为指导。burgdorferi基因组序列和引用的其他小组的工作，我们的假设将通过追求两个特定的目标进行测试：1）确定参与B适应的基因。鉴定B的晚期宿主适应因子。对哺乳动物感染很重要的伯氏螺旋体。在第一个目标下，我们将利用体内表达技术（IVET）。该系统将利用基于启动子的B基因组DNA文库。burgdorferi，其被设计为允许仅选择那些仅在小鼠宿主内有活性的启动子。第二个目标将利用IVET系统的修改版本，称为基于酶的IVET（RIVET）。该系统还将利用基于启动子的B基因组DNA文库。burgdorferi的启动子，但设计成仅允许选择那些在小鼠宿主中瞬时或在晚期感染期间有活性的启动子。拟议的工作是创新的，因为它利用了特定B的基本活动。burgdorferi蛋白作为鉴定重要毒力因子的新手段。当应用时，预期拟定研究的结果将允许靶向该系统，以显著降低该病原体在哺乳动物宿主中建立感染的能力。 公共卫生相关性：拟议的研究是莱姆病研究的一个重要领域，适用于了解伯氏疏螺旋体的感染性和发病机制。拟议的研究与公共卫生有关，因为由此产生的发现有可能从根本上推动B领域的发展。burgdorferi适应性基因的表达，并可能对其他动物和人类病原体的宿主适应系统具有广泛的影响。因此，这些发现最终有望适用于人类的健康。

DESCRIPTION (provided by applicant): Borrelia burgdorferi is an obligate parasite, and is maintained in nature through a complex cycle involving both a tick and mammalian host. The transition between these two very different host types requires the ability to rapidly adapt through changes in gene expression. Artificial infection studies have provided information on a number of these genes that may be differentially expressed under conditions similar to that of the vertebrate host. Despite this advance, there remains a fundamental gap in our understanding of the role and function of a number of genes for mammalian host adaptation. Our long-term goal is to identify and characterize the proteins necessary for adaptation of B. burgdorferi to both the tick and mammalian host environments. The overall objective of this application is to identify B. burgdorferi candidate genes required for adapting specifically to the mammalian host using a mouse model. The central hypothesis is that a large number of B. burgdorferi genes of unknown function are adaptively expressed. Furthermore, we hypothesize that a number of genes important for host adaptation are either transiently expressed, or are turned on only during late-stage infection of mice. The rationale for the proposed research is that, once the genes involved in adapting to the host environment have been identified, it will be possible to determine their respective roles in establishing mammalian infection. 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 the published B. burgdorferi genome sequence and cited work by other groups, our hypothesis will be tested by pursuing two specific aims: 1) Identify genes involved in the adaptation of B. burgdorferi to the mammalian host environment; and 2) Identify late-stage host adaptation factors of B. burgdorferi important for mammalian infection. Under the first aim, we will make use of In Vivo Expression Technology (IVET). This system will utilize a promoter-based genomic DNA library of B. burgdorferi that is designed to allow for the selection of only those promoters that are active exclusively within the mouse host. The second aim will utilize a modified version of the IVET system, termed Recombinase-based IVET (RIVET). This system will also make use of a promoter-based genomic DNA library of B. burgdorferi, but is designed to allow for the selection of only those promoters that are active transiently or during late-stage infection in the mouse host. The proposed work is innovative because it capitalizes on the essential activities of specific B. burgdorferi proteins as a new means of identifying important virulence factors. When applied, the results from the proposed studies are expected to allow the targeting of this system in order to significantly reduce the ability of this pathogen to establish infection in the mammalian host. PUBLIC HEALTH RELEVANCE: The proposed studies are of an important area of Lyme disease research that has applicability to understanding infectivity and pathogenesis by Borrelia burgdorferi. The proposed research has relevance to public health because the resulting discoveries have the potential to fundamentally advance the field of B. burgdorferi adaptive gene expression, and may have broad implications for host adaptation systems in other animal and human pathogens. Thus, the findings are ultimately expected to be applicable to the health of human beings.