Population Genetic Structure of Ixodes scapularis and disease transmission

描述（由申请人提供）：本研究项目的长期目标是通过研究美国南部节肢动物媒介的群体遗传学来提高我们对莱姆病（LD）传播的理解。这种综合的生态学方法将提供重要的信息能力的I。肩胛肌为B。当从不同脊椎动物宿主物种取食时，通过利用得克萨斯州地理气候不同地区之间的生态变化，这项研究将提供 一个生态和遗传框架，以表征LD在美国中南部传播给人类。LD是美国最流行的节肢动物传播疾病，2011年向CDC报告了33，097例病例。迄今为止完成的几乎所有LD研究都集中在这种疾病更普遍的美国东北部和中西部地区，没有在美国南部进行重大研究。有一个关键的需要，以确定生态因素，促进LD的差异发病率，即使代理，载体和哺乳动物宿主存在于两个地理区域。此外，关于I.肩胛肌和作用，这种遗传多样性在解释风险承包LD。我们将利用最近对其他蜱类的宿主利用生态学和遗传学的了解作为基线，以探索同样的现象是否发生在I。肩胛肌宿主的可用性、多样性和丰度在空间和时间尺度上都有差异。因此，给定病媒物种的个体可能在不同的环境中受到不同的选择压力。 其分布的地理位置。这可能会导致病媒种群根据地理位置、宿主物种或两者的组合进行结构化。在其最基本的水平上，了解空间变异的模式，在主机使用的动物疾病的多食性载体，需要收集主机使用的数据在精细和课程的分辨率。因此，我们将通过提出两个具体目标来处理这个问题。具体目标1：量化本地主机使用模式和B。在得克萨斯州的两个截然不同的环境（松林和后橡树萨凡纳）内，肩胛硬蜱的burgdorferi感染I.肩胛肌我们还将测试脊椎动物宿主群落、蜱流行率和B的差异。在选定的得克萨斯州生态区，退化的森林生境和退化的森林生境之间的伯氏螺旋体感染。(Dr. Esteve-Gassent，Dr. Castro-Arellano）.具体目标2：我们将测试的遗传群体结构和主机相关的遗传分化的I。在上述不同的生态区域中，肩胛肌的分布情况（麦地那博士）。在这些研究完成后，我们期望我们将确定本地宿主使用I的模式。肩胛肌，以及与宿主相关的遗传差异。我们还期望已经描绘出B的分布。burgdorferi在研究的脊椎动物宿主，并评估他们的能力，这种病原体在得克萨斯州的水库。

DESCRIPTION (provided by applicant): The long-term goal of this research project is to improve our understanding of Lyme disease (LD) transmission through the study of the population genetics of the arthropod vector in the Southern US. This integrated ecological approach will provide significant information on the competence of I. scapularis as a B. burgdorferi vector when feeding from different vertebrate host-species. By capitalizing on the ecological variation among geo-climatically distinct regions in Texas, this study will provide both an ecological and genetic framework to characterize the transmission of LD to humans in the South-Central United States. LD is the most prevalent arthropod-borne disease in the US with 33,097 cases reported to the CDC during 2011. Almost all LD studies completed to date are focused in the Northeast and Midwest regions of the US where this disease is more prevalent, with no major studies done in Southern US. There is a critical need to determine the ecological factors promoting the differential incidence of LD even though the agent, vector and mammalian hosts are present in both geographic regions. In addition, there is limited information on the genetic diversity of I. scapularis and on the role this genetic diversity has in explaining the ris of contracting LD. We will use recent insights into the host use ecology and genetics of other tick species as a baseline to explore if the same phenomenon occurs in I. scapularis. Host availability, diversity and abundance vary across both spatial and temporal scales. Therefore, individuals of a given vector species may be subjected to distinct selective pressures in different geographic portions of its distribution. This may result in vector populations being structured by geography, host species or a combination of both. At its most basic level, understanding patterns of spatial variation in host use by polyphagous vectors of animal diseases, requires the collection of host use data at both fine and course resolutions. Consequently, we will approach this issue by proposing two specific aims. Specific Aim 1: Quantify local host use patterns and B. burgdorferi infection in Ixodes scapularis in two contrasting environments in Texas (Pinewoods and Post Oak Savannah) within the geographic distribution of I. scapularis. We will also test for differences of vertebrate host communities, tick prevalence and B. burgdorferi infection between anthropogenically degraded and sylvan habitats at the selected Texas eco- regions. (Dr. Esteve-Gassent, Dr. Castro-Arellano). Specific Aim 2: We will test for genetic population structure and host associated genetic differentiation of I. scapularis across the different eco-regions outlined above (Dr. Medina). At the completion of these studies, it is our expectation that we will have identified the local host use patterns of I. scapularis, as well as te host associated genetic differences. We also expect to have delineated the distribution of B. burgdorferi in the studied vertebrate hosts and evaluated their competence as reservoirs for this pathogen in the state of Texas.