Evolutionary and Functional Significance of Novel Mutations in MDR-XDR TB

描述（由申请人提供）：去年报告了900多万例活动性结核病和100万例结核病死亡。耐药结核分枝杆菌的发展正在增加，并威胁到结核病控制工作。全球耐药结核病和诊断联合会（GCDD）已经确定了超过100个（419个）耐药结核病分离株，没有已知的耐药突变。此外，GCDD还在其四个研究地点（印度、摩尔多瓦、菲律宾和南非）确定了七个不同的区域基因型-表型关系。 一线和二线药物，这表明结核分枝杆菌在每个位点采取不同的进化途径来耐药。这也可能意味着Mtb正在使用不同的机制在这些研究地点产生耐药性，因此可能很快需要针对每个进化路径/研究地点的一套新的抗结核药物。虽然不同进化路径的出现可能是由于抗TB药物的可变可用性，但是这种独特性的出现是令人担忧的，并且如果继续下去，Mtb可以进化成不同的完全耐药状态（TDR-TB），从而导致需要区域特定治疗和公共卫生策略的流行病。该项目旨在通过对新发现的与耐药性相关的基因和调控元件进行计算机功能表征，揭示以前未知的耐药性机制。这将解释无法解释的抵抗案例。功能表征将允许鉴定涉及这些新突变的每种药物的耐药机制，鉴定可导致对多种药物耐药的“关键”突变，并鉴定可作为新药靶点的功能相互作用网络中的中心位点。该项目还将对所有400多个GCDD Mtb基因组进行系统发育分析。新的和已知的突变的功能表征和耐药性的进化分析的组合将回答不同的进化路径和耐药机制是否是现实。如果是这样的话，该模型可以扩展到预测未来的区域演化趋势。实验性重组技术将用于确认实验室中导致耐药性的关键突变的重要性。

DESCRIPTION (provided by applicant): Last year over 9 million cases of active TB and 1 million deaths due to TB were reported. The development of drug-resistant Mtb is increasing and threatens TB control efforts. Global Consortium for Drug-resistant TB and Diagnostics (GCDD) has identified over 100 (out of 419) resistant Mtb isolates without known resistance-causing mutations. Additionally, GCDD has identified distinct regional genotypic-phenotypic relationships at its four study sites (India, Moldova, the Philippines, and South Africa) for seven first and second line drugs, suggesting that Mtb is taking a different evolutionary route to resistance at each site. This could also mean that Mtb is using different mechanisms for producing resistance at these study sites and therefore could soon require new set of anti-TB drugs for each evolutionary path/study site. While the emergence of the distinct evolutionary paths are probably due to variable availability of anti-TB drugs, the emergence of this distinctiveness is alarming and if continued, Mtb can evolve into different states of total drug resistance (TDR- TB) causing an epidemic that requires region-specific treatment and public health strategy. This project aims to uncover previously-unknown mechanisms of drug resistance through in silico functional characterization of newly identified gene and regulatory elements associated with drug resistance. This will explain the unexplained cases of resistance. The functional characterization will allow the identification of the mechanism of resistance for each drug involving these novel mutations, identification of "keystone" mutations that can cause resistance to multiple drugs, and identify central loci in the functional interaction network that can serve as new drug targets. This project will also perform a phylogenetic analysis of all 400+ GCDD Mtb genomes. The combination of functional characterization of novel and known mutations and the evolutionary analysis of drug resistance will answer whether distinct evolutionary paths and mechanisms of resistance are a reality or not. If so, the model can be extended to predict future regional evolutionary trends. Experimental recombinant technology will be used to confirm the significant the keystone mutations responsible for resistance in the laboratory.