Molecular Epidemiology of Leprosy

描述(由申请人提供)：2002年发现了67万例新的麻风病例。尽管在过去10-20年里，世界卫生组织实施了有效的多种药物疗法来治疗麻风病患者，但造成这一高发病率的因素是什么？对于麻风病，麻风分枝杆菌的潜在传播机制仍然不清楚，关于来源、宿主、传播方式和与宿主的相互作用。存在多种假说，但由于无法在体外培养麻风杆菌，疾病发病缓慢，以及临床表现的广泛性，答案仍然是推测的。最近获得的麻风分支杆菌分离株的基因组序列是适用于麻风流行病学的有价值的新资源。这项提案提出了一种独特的办法，旨在共同努力研究多种因素，以便更全面地了解麻风病持续发生的最合理原因。其目标是通过开发和应用灵敏、特定和简单的分子方法，推动几个独立实验室的研究工作。其具体目的是：1.通过对土壤和水中麻风支原体特异性DNA和mRNA的聚合酶链式反应(PCR)扩增；以及对麻风流行地区发现的临床菌株进行菌株分型，以评估人类以外环境对麻风传播的贡献；2.通过对麻风接触者接触者的亚临床感染进行评估：a)对麻风支原体特异性DNA和mRNA进行聚合酶链式反应(PCR)扩增；b)菌株分型，与临床病例中发现的临床菌株进行比较；以及c)显示参与感染和免疫的细胞因子的mRNA；3.通过以下方法评估麻风发病病例的贡献：a)用聚合酶链式反应扩增麻风支原体特异的DNA和mRNA；b)与流行病学相关病例进行比较；c)鉴定FolP和rpoB基因突变导致的原发和获得性耐药性，这两个基因分别是氨苯松和利福平的靶标。用菌株分型方法证明麻风杆菌在传播链中的身份是很重要的。应用新发现的9个多态基因座进行菌株分型是这一建议的关键组成部分。预计这项研究投资将产生的实际解决方案和知识数据库将对麻风病最流行地区的传播监测和控制以及麻风菌毒力、进化和致病性的研究产生切实影响。

DESCRIPTION (provided by applicant): 670,000 new cases of leprosy were detected during the year 2002. What are the factors that contributed to this high incidence even though effective multidrug therapy implemented by the World Health Organization has been used to treat leprosy patients over the last 10-20 years? For leprosy, the underlying mechanisms of transmission of Mycobacterium leprae, the causative organism, are still unclear with respect to the source, reservoir, mode of transmission and interaction with the host. Multiple hypotheses exist, but answers remain speculative owing to the inability to cultivate M. leprae in vitro, the slow onset of disease, and the broad spectrum of clinical manifestations. The recent availability of the genome sequence of an isolate of M. leprae is a valuable new resource applicable to the epidemiology of leprosy. This proposal presents a unique approach aimed at a concerted effort to study multiple factors in order to obtain a more comprehensive understanding of the most plausible causes for continued incidence of leprosy. The objectives are to advance the research endeavors at several independent laboratories through development and application of sensitive, specific and simple molecular methods. The specific aims are: 1.To evaluate the contribution of the extra-human environment in leprosy transmission by: a) PCR amplification of M. leprae specific DNA and mRNA in soil and water; and b) strain typing for comparison with clinical strains found in the endemic region; 2. To evaluate sub-clinical infections in contacts of leprosy patients by: a) PCR amplification of M. leprae specific DNA and mRNA; b) strain typing for comparison with clinical strains found in index cases; and c) demonstration of mRNA of cytokines involved in infection and immunity; and 3. To evaluate the contribution of incident leprosy cases by: a) PCR amplification of M. leprae specific DNA and mRNA; b) strain typing for comparison with epidemiologically linked cases and; c) identification of primary and acquired drug resistance conferred by mutations in folP and rpoB genes, targets of dapsone and rifampicin respectively. It is important to prove identity of M. leprae within the chain of transmission by strain typing methods. The application of nine newly discovered polymorphic loci for strain typing is a key component of this proposal. It is envisioned that the practical solutions and the knowledge database that will emerge from this research investment will have a tangible impact on leprosy surveillance and control of transmission in the most endemic areas and to studies regarding virulence, evolution and pathogenicity of M. leprae.