Role in pathogenesis and parasite cell biology of the trans-sialidase from Trypan

描述（申请人提供）：恰加斯病，美洲锥虫病，是由鞭毛虫原生动物克氏锥虫引起的一种慢性致残性寄生虫病。它被认为是一种被忽视的热带病。据估计，总共有1亿人面临感染风险，大约800万至1000万人已经受到感染，每年新增病例约40 000例，恰加斯病是拉丁美洲的一个重大卫生、社会和经济问题。该感染由锥蝽病媒（“接吻虫”）自然传播，从美国南部传播到南美洲南部。然而，由于从流行地区向经济发达国家的移民，恰加斯病患者实际上分散在世界各地。因此，恰加斯病正在许多非流行国家（澳大利亚、日本、西班牙等）出现。阿根廷的感染者估计约为160万人，美国约为30万至100万人。虽然在其生命周期中至关重要，但克氏绦虫不能合成唾液酸。寄生虫通过一种被称为反式唾液酸酶的酶从哺乳动物宿主那里清除糖缀合物。这种酶是一种诱导宿主免疫系统改变的毒力因子，有利于寄生虫的定植过程。我们的长期目标是充分阐明该毒力因子与寄生虫生物学、生命周期毒力和发病机制的相关性，并了解其对免疫系统生理的影响。了解病原体对免疫反应的操纵可以更好地对抗感染，也有助于更多地了解免疫系统生理学，并最终将这些知识转移到其他病理（自身免疫性疾病，移植排斥反应，炎症反应等）的治疗处理中。本项目旨在揭示反式唾液酸酶受体分子在寄生虫和淋巴细胞表面获得唾液酸残基的过程与寄生虫发病机制和生物学在细胞和分子水平上的相关性。为了实现这些目标，我们将a)使用转染了修饰转运蛋白的转基因寄生虫来准确确定TS细胞内运输；B)采用非天然糖方法作为生物正交化学报告者，清楚地识别受体分子及其在寄生虫和白细胞表面的命运和功能；c)利用t细胞受体转基因和KO小鼠模型寻找已知免疫反应的诱导改变；d)检测转基因寄生虫，分析TS失活异构体与毒力因子和发病机制的关系。

DESCRIPTION (provided by applicant): Chagas disease, the American trypanosomiasis, is a chronic disabling parasitic disease caused by the flagellate protozoon Trypanosoma cruzi. It is considered a neglected tropical disease. With an estimated total of 100 million people at risk, about 8-10 million already infected, and about 40,000 new cases/year, Chagas disease represents a major health, social and economic problem in Latin America. The infection is naturally transmitted by triatomine vectors ("kissing bugs"), from the southern USA to the south of South America. However, chagasic patients are in fact dispersed worldwide due to migration from the endemic region to economically-developed countries. Therefore, Chagas disease is emerging in many non-endemic countries (Australia, Japan, Spain, etc). Infected people in Argentina are estimated at about 1,600,000 and in the USA at about 300,000-1,000,000. Although crucial in its life cycle, T. cruzi is unable to synthesize sialic acids. The parasite scavenges it from the mammalian host glycoconjugates through an enzyme known as trans-sialidase. This enzyme is a shed virulence factor that induces alterations in the host immune system, favoring the parasite colonization process. Our long-term aim is to fully clarify the relevance of this virulence factor to parasite biology, life cycle virulence and pathogenesis, and to understand the alterations induced on the immune system physiology. Understanding the manipulation of the immune response by pathogens allows a better fight against the infection and also helps to learn more about the immune system physiology, and eventually to transfer this knowledge to the therapeutic handling of other pathologies (autoimmune diseases, transplant rejection, inflammatory responses, etc.). This project proposes to disclose the relevance -to pathogenesis and parasite biology, at cellular and molecular levels- of the acquisition process of the sialyl residue performed by the trans-sialidase acceptor molecules on the parasite and lymphocyte surfaces. To achieve these goals we will a) use genetically-modified parasites transfected with modified transporters to accurately determine TS intracellular trafficking; b) follow the unnatural sugars approach as bioorthogonal chemical reporters to clearly identify acceptor molecules and their fate and function on parasite and white cell surfaces; c) search for the induced alterations of known immune responses using T-cell receptor transgenic and KO mice models; and d) test genetically-modified parasites to analyze the association of TS inactive isoforms with virulence factors and pathogenesis.