The Genetic Basis of Bone Disease in Mycobacterial Infection

 描述(申请人提供)：结核分枝杆菌感染每年导致100多万人死亡。虽然结核病通常仍局限于肺部，但分枝杆菌也能够传播到包括骨骼在内的其他组织。导致感染部位的细菌和宿主因素的相互作用，特别是骨感染，目前还不完全清楚。我们已经确定了一种暴发菌株，我们在临床上发现这种菌株具有较高的肺外播散率和前所未有的结核性骨病发病率。我们正在分析这种独特的结核分枝杆菌分离株，以确定哪些菌株的特定因素可能导致骨感染的倾向。我们已经对NCG基因组进行了测序和组装，发现它是一个古老分支的成员。我们假设，NCG菌株的独特遗传变异赋予了骨嗜性。为了了解强毒分枝杆菌与骨骼的相互作用，我们将1)建立斑马鱼模型，直接研究分枝杆菌感染过程中的传播和骨骼疾病。骨组织由骨形成成骨细胞和骨吸收破骨细胞持续重塑；其中一个或两个过程的不平衡可能导致骨骼疾病。利用斑马鱼模型，我们将在整个活体动物中实时观察分枝杆菌感染对骨组织重塑的影响。2)我们将识别爆发菌株基因组中的独特变异，并利用斑马鱼平台来评估它们在骨骼疾病中的功能相关性。3)在一种平行的方法中，我们将使用小鼠模型来询问和验证使用气溶胶感染暴发菌株的特定遗传变异。这些研究将提供对特定基因变异在感染暴发菌株过程中的作用和意义的见解，以及分枝杆菌传播和骨骼疾病的基础。

 DESCRIPTION (provided by applicant): Mycobacterium tuberculosis infections kill more than one million people annually. Although tuberculosis generally remains confined to the lung, mycobacteria also are able to disseminate to other tissues including bone. The interplay of bacterial and host factors that contribute to infection site, particularly bone infection, is incompletely understood. We have identified an outbreak strain that we find clinically to present with high rates of extrapulmonary dissemination and an unprecedented rate of tuberculous bone disease. We are analyzing this unique isolate of Mycobacterium tuberculosis to determine what strain- specific factors may be responsible for the proclivity to cause bone infection. We have sequenced and assembled the NCG genome and find that is a member of an ancient clade. We hypothesize that unique genetic variants of the NCG strain confer bone tropism. In order to understand the interactions of virulent mycobacteria with bone, we will 1) develop a zebrafish model to directly examine dissemination and bone disease during mycobacterial infection. Bone tissue is continuously remodeled by bone-forming osteoblasts and bone-resorbing osteoclasts; an imbalance in either or both processes can result in bone disease. Using a zebrafish model, we will observe in whole live animals in real time the impact of mycobacterial infection on bone tissue remodeling. 2) We will identify unique variants in the outbreak strain genome and use the zebrafish platform to assess their functional relevance in bone disease. 3) In a parallel approach, we will use mouse models to interrogate and validate specific genetic variants using aerosol infections with the outbreak strain. These studies will provide insights into the functiona significance of specific genetic variants during infection with an outbreak strain as well as the basis of mycobacterial dissemination and bone disease.