Low temperature survival of Borrelia burgdorferi in overwintering ticks

描述（由申请方提供）：伯氏疏螺旋体是莱姆病的螺旋体，通过受感染的硬蜱叮咬传播时会导致人类疾病。硬蜱获得B。burgdorferi作为幼虫以感染的哺乳动物为食; B.在蜱的中肠越冬。幼虫在春季蜕皮成为传播B的媒介。burgdorferi到人类。该项目的长期目标是确定B.布格氏蜱虫在冬季的低温中生存。揭示这些生存策略实现了该机构的使命，因为拟议的实验将阐明这种病原体的一个关键生物学特性，并提供减少B的潜在目标。因此，本发明的方法可以降低蜱虫体内伯氏螺旋体的存活力，从而降低人类感染的可能性。要检验的假设是，MalQ，一个？葡聚糖转移酶产生B必需的冷冻保护剂二糖。burgdorferi在低温下生存，并在蜱虫中持续越冬。这一假设将在具体目标1中通过实验加以解决。第一个目标将检查诱导malQ转录和蛋白质表达的条件。假设低温和可能的蜱相关因素将诱导malQ表达。第二个目标是确定B。burgdorferi产生海藻糖，并且如果产生依赖于malQ。第三个目标将是确定是否B。burgdorferi在低温下的存活是malQ依赖的。第四个也是最后一个目标是检查是否B。在低温条件下，伯氏硬蜱在肩突硬蜱体内的存活是malQ依赖的。具体目标2的重点是进行遗传筛选，以确定与低温下生存有关的其他因素。为了实现这一目标，水手转座子系统适用于B。burgdorferi将用于使基因组充满标记的突变。低温生长试验将鉴定存活受到损害的突变体。已被转座子破坏的基因将被鉴定，因此，与低温下的生长和越冬蜱载体中的存活有关。 公共卫生相关性：莱姆病的发病率在过去15年中稳步上升，2007年美国报告了超过27，000例新病例。B。莱姆病的病原体伯氏莱姆病，在蜱的两年生命周期中存在于蜱的中肠中，并通过蜱叮咬传播给人类。通过研究B.伯氏菌在蜱虫体内越冬我们希望揭示这种细菌在低温下生存的分子机制，并在每年夏天作为一种有问题的人类病原体出现。

DESCRIPTION (provided by applicant): Borrelia burgdorferi, the spirochete responsible for Lyme borreliosis, causes disease in humans when transmitted by the bite of infected Ixodes ticks. Ixodes acquire B. burgdorferi as larvae feed on infected mammals; B. burgdorferi survive in the tick midgut over winter. The larvae molt into nymphs in the spring to emerge as the vector that transmits B. burgdorferi to humans. The long-term goal of this project is to determine the molecular mechanisms that B. burgdorferi employ to survive the low temperatures in the tick during winter. Uncovering these survival strategies fulfills the mission of the agency as the proposed experiments will elucidate a key biological property of this pathogen and provide potential targets to reduce B. burgdorferi viability in tick nymphs, and thus reducing the likelihood of human infection. The hypothesis to be tested is that MalQ, an ?-glucanotransferase, produces cryoprotectant disaccharides that are essential for B. burgdorferi to survive at low temperatures and persist in ticks over winter. This hypothesis will be experimentally addressed in specific Aim 1. The first goal will examine the conditions that induce malQ transcript and protein expression. The hypothesis is that low temperature, and possibly tick-related factors, will induce malQ expression. The second goal will be to determine if B. burgdorferi produces trehalose and if production is dependent on malQ. The third goal will be to determine if B. burgdorferi survival at low temperature is malQ-dependent. The fourth and final goals are to examine if B. burgdorferi survival in Ixodes scapularis at low temperature is malQ-dependent. A genetic screen to identify additional factors involved in survival at low temperatures will be the focus of specific Aim 2. To accomplish this aim, the mariner transposon system adapted for B. burgdorferi will be used to saturate the genome with marked mutations. Low temperature growth assays will identify mutants whose survival has been compromised. Genes that have been disrupted by the transposon will be identified and, thus, implicated in growth at low temperatures and survival in the overwintering tick vector. PUBLIC HEALTH RELEVANCE: The incidence of Lyme borreliosis has steadily increased over the past 15 years with over 27,000 new cases reported in the United States in 2007. B. burgdorferi, the causative agent of Lyme disease, resides in the tick midgut throughout the tick's two year life cycle and is transmitted to humans by tick bite. By studying how B. burgdorferi overwinters in the tick we hope to uncover the molecular mechanisms that allow this bacterium to survive at low temperatures and emerge each summer as a problematic human pathogen.