Virulence factors in the pathogenesis of Chagas Disease

描述（由申请人提供）：克氏锥虫是南美锥虫病或美洲锥虫病的病原体。南美锥虫病仍然是拉丁美洲的一个相关传染性死因，每年至少有50 000人死亡，许多年轻男子因无法从事农村工作而对其家庭造成严重的经济影响。据估计，18，000，000人已经受到感染，100，000，000人面临感染风险，每年有200，000个新病例。这种疾病还通过子宫和受污染的血液传播，将感染风险扩大到流行地区之外。尽管这种寄生虫不能从头合成唾液酸，但其对宿主细胞的附着和侵入以及其对血清溶解因子的物理保护取决于其膜锚定组分的唾液酸化。为了规避这一缺口，寄生虫在其表面上表达一种新的转唾液酸酶（TS）活性，其从宿主糖缀合物中清除唾液酸残基并使用它们来转糖基化其自身的受体分子。没有描述类似的哺乳动物酶。除了寄生虫表面相关的作用，TS还流入血液。全身分布的酶通过诱导免疫系统不同细胞的细胞凋亡、血小板减少症和红细胞增多症，触发与疾病急性期相关的几种病理学发现。通过中和抗体控制该毒力因子导致预防所有这些异常，然后提示化疗的靶点。本申请旨在获得对TS在感染期间所起的多种致病作用的新的细胞和分子见解，并获得可能用于化疗的抑制剂的合理设计的线索。将通过标记糖和质谱鉴定作为TS靶点的免疫细胞糖缀合物，以获得有关细胞机制的知识。修饰的表面分子与内源性配体的相互作用，导致相关的死亡机制也将被搜索。通过使用卵清蛋白特异性TCR转基因小鼠来确定TS诱导的免疫系统损伤反映在持续的免疫应答上的程度。TS抑制的结构基础将通过具有高亲和力中和单克隆抗体的二元复合物的3D分辨率来分析。公共卫生相关性：美洲锥虫病是一种慢性寄生虫病，是拉丁美洲的一个重大健康、社会和经济问题。据估计，克氏锥虫感染的流行率约为1 800万例，约有1亿多人处于危险之中，每年有20万新病例，约有500万人出现可归因于恰加斯病的临床变化。治疗不令人满意，主要是因为疗效不确定，而且现有药物很少，副作用严重。

DESCRIPTION (provided by applicant): Trypanosoma cruzi is the causative agent of Chagas disease or American Trypanosomiasis. Chagas Disease continues to be a relevant infectious cause of death in Latin America where at least 50,000 people dies every year and many young men became disabled to rural work with high economic impact to their families. It is estimated that 18,000,000 persons are already infected and 100,000,000 are at risk of infection with 200,000 new cases/year. The disease is also transmitted in uterus and by contaminated blood extending the risk of infection out of the endemic regions. Even though this parasite is unable to synthesize sialic acids de novo, its attachment to, and invasion of host cell as well as its physical protection against serum lytic factors depend upon the sialylation of its membrane-anchored components. To circumvent this gap, the parasite expresses a novel trans-sialidase (TS) activity on its surface, which scavenges sialyl residues from host glycoconjugates and use them to trans- glycosylate its own acceptor molecules. No similar mammal enzyme is described. In addition to the parasite surface-associated role TS is shed into the bloodstream. The systemically distributed enzyme triggers several of the pathologic findings associated to the acute phase of the disease by inducing apoptosis on different cells of the immune system, thrombocytopenia and erythropenia. The control of this virulence factor by neutralizing antibodies results in prevention of all those abnormalities then suggesting a target for chemotherapy This Application points to get novel cellular and molecular insights into the multiple pathogenic roles played by TS during infection and to obtain clues for the rational design of inhibitors that might be used in chemotherapy. The immune cells glycoconjugates involved as targets of the TS will be identified by tagged sugars and mass spectra to gain knowledge on the cellular mechanisms involved. The interaction of the modified surface molecules with the endogenous ligands that leads to the associated mechanisms of death will be also searched. The extent to which the immune system damage induced by the TS is reflected on the ongoing immune response will be determined by using ovalbumin specific TCR transgenic mice. The structural basis of the TS inhibition will be analyzed by the 3D resolution of the binary complex with a high affinity neutralizing monoclonal antibody. PUBLIC HEALTH RELEVANCE: Chagas disease, the American trypanosomiasis, is a chronic parasitic illness that represents a major health, social and economic problem in Latin America. The prevalence of Trypanosoma cruzi infection has been estimated as about 18 million cases, with about 100 million more people at risk and 200,000 new cases/year with about 5 million people having clinical changes attributable to Chagas disease. Treatment is unsatisfactory mainly because dubious outcome and serious adverse effects of the few available drugs.