Genetic Basis of Mycobacterial Invasion

描述（由申请人提供）：结核病是全球最大的传染性疾病和死亡原因之一。近年来，由于出现耐药菌株和同时发生的艾滋病毒流行病，这一问题更加严重。目前还没有可靠的结核病疫苗，越来越多的证据表明，自然感染和疾病不能防止随后的再感染。因此，宿主免疫在预防和消除感染方面仅部分有效。为了帮助理解结核病在宿主免疫背景下的基本发病机制，我们将使用密切相关的致病种海洋分枝杆菌，外温动物的系统性结核病样疾病和人类的外周肉芽肿性疾病的代理。由于海洋分枝杆菌与结核分枝杆菌在遗传和致病性上的相似性，它已成为结核病的一个强有力的模型。结核病，其相对快速的增长，以及作为动物模型的多种自然宿主的存在。我们使用成年豹蛙和斑马鱼研究发病机制以及斑马鱼胚胎，由于其光学透明度，可以实时监测宿主-病原体相互作用。利用胚胎模型结合M.通过我们先前鉴定的海洋性肉芽肿激活基因，我们已经能够实时监测肉芽肿的形成。我们将继续使用所有这些模型来确定分枝杆菌如何在体内面对强大的宿主免疫应答时持续存在。我们将使用斑马鱼胚胎模型来确定已知分枝杆菌毒力基因减毒的细胞机制，并在此过程中，对导致慢性感染的事件有一个全面的了解。作为第一步，我们已经确定RD 1毒力基因座特异性地促进体内巨噬细胞的聚集。我们将研究在体内贩运的野生型和突变株的海洋分枝杆菌在以前形成的肉芽肿的背景下，特别注意的作用，酪蛋白。最后，我们将进行实验，以直接确定位于慢性肉芽肿内的分枝杆菌的生理和复制状态。这些实验将确定这些细菌是处于静止状态还是正在积极复制。从我们提出的实验中获得的信息将进一步加深我们对结核病中宿主-病原体相互作用的基础知识。

DESCRIPTION (provided by applicant): Tuberculosis is one of the greatest infectious causes of disease and mortality worldwide. The problem has been exacerbated in recent years by the emergence of drug resistant strains and the concurrent HIV epidemic. There is no reliable vaccine against tuberculosis and there is increasing evidence that natural infection and disease cannot prevent subsequent reinfection. Thus host immunity is only partially effective in preventing and eliminating infection. To aid in the understanding of the basic pathogenesis of tuberculosis in the context of host immunity, we will use a closely related pathogenic species Mycobacterium marinum, the agent of a systemic tuberculosis-like disease in ectotherms, and a peripheral granulomatous disease in humans. M marinum has become established as a powerful model for tuberculosis owing to its genetic and pathogenic similarities to M. tuberculosis, its relatively rapid growth, and the existence of multiple natural hosts that serve as animal models. We use adult leopard frogs and zebrafish to study pathogenesis as well as zebrafish embryos, which allow real-time monitoring of host-pathogen interactions due to their optical transparency. Using the embryo model in conjunction with M. marinum granuloma-activated genes that we previously identified, we have been able to monitor granuloma formation in real-time. We will continue to use all of these models to determine how mycobacteria persist in the face of a robust host immune response in vivo. We will use the zebrafish embryo model to determine the cellular mechanism of attenuation of known Mycobacterium virulence genes, and in so doing, develop an integrated understanding of the events leading to chronic infection. As a first step, we have already determined that the RD1 virulence locus specifically promotes the aggregation of macrophages in vivo. We will study the in vivo trafficking of wild type and mutant strains of M marinum in the context of previously formed granulomas, with special attention paid to the role of the caseum. Finally, we will perform experiments to directly determine the physiological and replicative state of mycobacteria located within chronic granulomas. These experiments will determine whether such bacteria are in a quiescent state or are actively replicating. The information obtained from our proposed experiments will further our fundamental knowledge about host-pathogen interactions in tuberculosis.