Study of cutaneous leishmaniasis in Sri Lanka caused by L.donovani

描述(申请人提供)：利什曼病造成的全球疾病负担很高，目前有多达1200万人感染，每年新增病例100-200万例，特别是在非洲、亚洲和南美洲。它被认为是研究最少、最被忽视的热带病之一。该病原体属于利什曼原虫属，它通过受感染的血吸虫沙蝇的叮咬传播。已知有20多种利什曼原虫会引起疾病，从自限性皮肤损害到潜在的致命内脏疾病，主要取决于引起疾病的寄生虫种类。最致命的疾病是由多诺瓦氏杆菌引起的，这种疾病主要流行于印度次大陆，其致病机制，特别是其表型变异，仍然知之甚少。斯里兰卡是受利什曼病影响的新疫源地，迄今收集的证据表明，存在遗传上不同的杜氏利什曼氏菌株，显示出非典型的嗜皮性表型特性，本文建议使用临床、生物学和最新的分子技术对其进行深入研究。深入了解杜氏钩端螺旋体中这种菌株的变异将有助于更好地了解该物种的毒力特性，进而将导致未来开发更有效的诊断和有效的治疗方法。这项建议的广泛目标是研究导致斯里兰卡皮肤利什曼病(CL)的杜诺瓦尼乳杆菌的表型和基因特征。具体地说，寄生虫的基本亲皮性将通过对CL的临床/病理后遗症的研究，通过使用临床和血清学标准对患者进行长期随访来确定。其次，在已建立的动物模型中，研究体内和体外寄生虫毒力，即巨噬细胞侵袭和疾病后遗症的相关性。第三，建议使用美国合作者建立的利什曼原虫微环DNA足迹分析方法对当地杜氏利什曼原虫菌株进行详细的遗传特征分析，作为区分物种间和物种内序列变异的有效方法。因此，当与印度和尼泊尔引起内脏疾病的菌株的类似数据一起分析时，这项测试将使斯里兰卡引起CL的寄生虫分离株能够进行深入的基因表征。总体而言，这项研究旨在更好地了解多诺瓦尼乳杆菌的致病性，从长远来看，这将有助于减轻全球疾病负担，为印度次大陆消除疾病的努力做出积极贡献。

DESCRIPTION (provided by applicant): The global disease burden due to leishmaniasis is high with as many as 12 million people currently infected, and 1-2 million new cases occurring each year, particularly in Africa, Asia and South America. It is considered as one of the least studied and most neglected of tropical diseases. The causative agent belongs to the genus Leishmania and it is transmitted via the bite of an infected phlebotomine sand fly. Over 20 species of Leishmania are known to cause diseases, which ranges from self-limiting cutaneous lesions to potentially fatal visceral disease, mainly depending on the causative parasite species. The most virulent form of disease is caused by L.donovani that is mostly prevalent in the Indian subcontinent and its pathogenetic mechanisms, particularly with regard to its phenotypic variants remain poorly understood. Sri Lanka is a new focus affected by leishmaniasis with the evidence gathered so far pointing towards the presence of genetically distinct strains of L.donovani that demonstrates an atypical phenotypic property of dermotropism, which is proposed here to be studied in depth using clinical, biological and latest molecular techniques. In depth understanding of such strain variations within the L.donovani species would enable better understanding of the virulent properties of this species and in turn would lead to the development of more efficient diagnostics and effective treatment methods in the future. The broad objective of this proposal is to study the phenotypic and genotypic characteristics of L.donovani that cause cutaneous leishmaniasis (CL) in Sri Lanka. Specifically, the essential dermotropic nature of the parasites will be determined through studies on the clinical/pathological sequelae of CL by long-term follow up of patients using clinical and serological criteria. Secondly, to study in vivo and in vitro correlates of parasite virulence, viz macrophage invasion and disease sequalae in established animal models. Thirdly, detailed genetic characterizations of local L.donovani strains is proposed to be done using Leishmania mini-circle DNA footprint assay, which has been established by the US collaborators, as an efficient and effective method to differentiate inter and intra-species sequence variations. Hence, this assay would enable in depth genetic characterization of parasite isolates that cause CL in Sri Lanka when analyzed together with similar data from strains that cause visceral disease in India and Nepal. Overall, this study is meant to enable better understanding of the pathogenicity of L.donovani, which in the long term would help reduce the global disease burden contributing positively towards the disease elimination efforts in the Indian subcontinent.