The Genetic Basis of Bone Disease in Mycobacterial Infection

 描述（由申请人提供）：结核分枝杆菌感染每年导致100多万人死亡。虽然结核病通常局限于肺部，但分枝杆菌也能够传播到其他组织，包括骨骼。细菌和宿主因素的相互作用，导致感染部位，特别是骨感染，是不完全了解。我们已经确定了一个爆发菌株，我们发现临床上目前与肺外传播率高，结核性骨病的前所未有的速度。我们正在分析这种独特的结核分枝杆菌分离株，以确定哪些菌株特异性因素可能是导致骨感染倾向的原因。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。为了了解毒性分枝杆菌与骨的相互作用，我们将1）开发一种斑马鱼模型，以直接检查分枝杆菌感染期间的传播和骨疾病。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导致骨病。利用斑马鱼模型，我们将在整个活体动物中真实的观察分枝杆菌感染对骨组织重建的影响。2)我们将确定爆发菌株基因组中的独特变异，并使用斑马鱼平台评估它们在骨骼疾病中的功能相关性。3)在一个平行的方法中，我们将使用小鼠模型来询问和验证特定的遗传变异，使用气溶胶感染爆发菌株。这些研究将为了解特定遗传变异在感染暴发菌株期间的功能意义以及分枝杆菌传播和骨骼疾病的基础提供见解。

 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.