TRYPANOSOME VARIANT SURFACE GLYCOPROTEIN CARBOHYDRATES

非洲锥虫病是一种影响非洲大片地区的寄生虫病 非洲大陆。它对人类构成威胁，并极大地阻碍 有效的养牛。这种传染病的病原体 是锥虫属的成员。这种寄生虫可以躲避哺乳动物 宿主对其存在于体液中的免疫应答 变异：一系列免疫上截然不同的表达 糖蛋白覆盖在侵袭性细胞的整个表面 有机体。这些变异的表面糖蛋白(VSG)有一个或多个 N-连接的多聚糖，并通过一种 糖基磷脂酰肌醇(GPI)部分。三类VSG中的一类 (根据C-末端氨基酸区分)，共价 只有两个VSG的GPI锚点和N-糖链的结构 I，只有一个锥虫种(布氏锥虫)已完全 已澄清。 拟议研究的主要目的是从结构上描述 几种锥虫VSG的GPI锚点和N-糖链的测定 这些低聚糖是否与 哺乳动物的糖蛋白。初步数据显示，GPI锚 锥虫体内的N-糖链与哺乳动物的不同 主持人。尤其是GPI主播被认为是主要的潜在目标 用于锥虫病的化疗。我们建议 六种锥虫VSGs的糖类结构特征 变异的抗原类型，并与哺乳动物的抗原类型进行比较 糖蛋白。我们特别建议： 1.从T.b.分离得到VSG及其糖类成分。 Rotdesiense LouTat 1和1A型(均为I级)和T.B.Rotdesiense 鲁塔特1.5和黄曲霉YNAT 1.1和1.3(均为II级)，生长在 啮齿动物和/或体外培养。获取III类VSG和GPI锚点 哺乳动物糖蛋白(人红细胞乙酰胆碱酯酶，AChE) 合作者。 2.对VSG GPI锚的结构进行表征并进行比较 和彼此在一起。寻找宿主对VSG GPI糖基化的影响。 将这些结构与AChE的GPI锚点的结构进行比较。 3.对来自VSG的N-聚糖进行结构表征 调查是否存在不寻常的结构元素。查找主机 对血管紧张素转换酶N-糖基化的影响。 我们的长远目标是为 化疗药物。建议的研究应提供 为进一步研究导致新的开发所需的基础 治疗非洲锥虫病的试剂。

African trypanosomiasis is a parasitic disease affecting large areas of the African continent. It presents a threat to man and drastically impedes effective cattle-rearing. The causative agents of this infectious disease are members of the genus Trypanosoma. The parasite evades the mammalian host's immunological response to its presence in body fluids by antigenic variation: the expression of a sequence of immunologically distinct glycoprotein coats over the entire surface of the cells of the invading organism. These variant surface glycoproteins (VSGs) have one or more N-linked glycans and are anchored in the trypanosome membrane by a glycosyl-phosphatidyl-inositol(GPI) moiety. Of the three classes of VSGs (distinguished on the basis of the C-terminal amino acid), the covalent structures of the GPI anchors and N-glycans of only two VSGs, both of class I, of only one trypanosome species (T. b. brucei) have been fully elucidated. The primary aim of the proposed research is to structurally characterize the GPI anchors and N-glycans of a variety of trypanosome VSGs to determine whether such oligosaccharides are significantly different to those of mammalian glycoproteins. Preliminary data indicate that the GPI anchors and the N-glycans of trypanosomes are different from those of the mammalian host. The GPI anchors in particular are considered prime potential targets for chemotherapeutic treatment of trypanosomiasis. We propose to characterize the carbohydrate structures of the VSGs of six trypanosome variant antigen types, and compare them with those of mammalian glycoproteins. In particular we propose to: 1. Isolate the VSGs and their carbohydrate moieties from T. b. rhodesiense LouTat 1 and 1A (both class I), and from T. b. rhodesiense LouTat 1.5 and T. congolense YNat 1.1 and 1.3 (all class II), grown in rodents and/or in vitro. Obtain a class III VSG and the GPI anchor from a mammalian glycoprotein (human erythrocyte acetylcholinesterase, AChE) from collaborators. 2. Characterize the structures of the VSG GPI anchors and compare them with each other. Look for host influence on VSG GPI glycosylation. Compare the structures to the structure of the GPI anchor of AChE. 3. Structurally characterize the N-glycans from the VSGs and investigate the presence of unusual structural elements. Look for host influence on VSG N-glycosylation. The long-term aim is to find a target for the development of chemotherapeutic agents. The proposed studies should provide the foundation necessary for further research leading to the development of new reagents for the treatment of African trypanosomiasis.