MCP：血吸虫幼虫和卵释放糖分子欺骗免疫系统致病机制

生物谷

   科学家发现导致血吸虫病的寄生虫幼虫和卵能释放一些糖分子，这些糖分子能引开免疫系统的注意，让寄生虫不被发现。

    这项研究发表在9月出版的《分子与细胞蛋白质组学》杂志上，它可能有助于开发新的疗法或者预防该病的疫苗。

    血吸虫是由裂体属吸虫导致的疾病，根据世界卫生组织的资料，它影响着非洲、亚洲和南美洲多达2亿人的健康。当人接触被污染的水源之后，这种寄生虫就能穿透人的皮肤从而感染人体。感染可能导致肝脏损伤、失血和死亡。

    来自英国约克大学和伦敦帝国理工学院的科学家分析了这种寄生虫幼虫和卵分泌的糖分子，结果发现了很多人体不具有的糖分子。

    约克大学的Alan  Wilson参与了这项研究，他告诉本网站说，这些糖分子会导致人体强烈的免疫应答。Wilson说，这是很不寻常的，因为通常寄生虫要躲避宿主的免疫系统。现在这种情况看上去就像寄生虫使用糖分子引开免疫系统，从而让幼虫和卵不被发现。

    尽管这项研究的前景看好，Wilson说开发疫苗的努力还没有产生成果。他说：“如果我们打算用疫苗打败这种寄生虫，我们需要对抗它使用过的所有策略，包括这种‘烟幕弹’策略。我们的研究给出了这种策略的分子基础。”

    Wilson告诉本网站说，未来的研究将着眼于成虫分泌的糖分子。成虫可以在人类血液中至多生活30年以上。他说：“很明显，它必须使用一些非常狡猾的机制，从而不被非常不利于它的环境影响。”

    埃及坦塔大学的医学教授Morad  Ahmed  Morad告诉本网站说，这项工作为这种寄生虫的生命周期提供了一些见解，而且可能有助于克服疫苗研发的一些困难。（农博网）

原始出处:

Molecular & Cellular Proteomics 6:1485-1499, 2007.

Glycomics Analysis of Schistosoma mansoni Egg and Cercarial Secretions*,S

Jihye Jang-Lee ${ddagger}$ , Rachel S. Curwen $§$ , Peter D. Ashton $§$ , Bérangère Tissot ${ddagger}$ , William Mathieson $§$ , Maria Panico ${ddagger}$ , Anne Dell ${ddagger}$ ,¶, R. Alan Wilson $§$ and Stuart M. Haslam ${ddagger}$ ,||

From the ${ddagger}$ Division of Molecular Biosciences, Imperial College London, London SW7 2AZ, United Kingdom and $§$ Department of Biology, University of York, York YO10 5YW, United Kingdom

The parasitic helminth Schistosoma mansoni is a major public health concern in many developing countries. Glycoconjugates, and in particular the carbohydrate component of these products, represent the main immunogenic challenge to the host and could therefore represent one of the crucial determinants for successful parasite establishment. Here we report a comparative glycomics analysis of the N- and O-glycans derived from glycoproteins present in S. mansoni egg (egg-secreted protein) and cercarial (0–3-h released protein) secretions by a combination of mass spectrometric techniques. Our results show that S. mansoni secrete glycoproteins with glycosylation patterns that are complex and stage-specific. Cercarial stage secretions were dominated by N-glycans that were core-xylosylated, whereas N-glycans from egg secretions were predominantly core-difucosylated. O-Glycan core structures from cercarial secretions primarily consisted of the core sequence Galß1 $->$ 3(Galß1 $->$ 6)GalNAc, whereas egg-secreted O-glycans carried the mucin-type core 1 (Galß1 $->$ 3GalNAc) and 2 (Galß1 $->$ 3(GlcNAcß1 $->$ 6)GalNAc) structures. Additionally we identified a novel O-glycan core in both secretions in which a Gal residue is linked to the protein. Terminal structures of N- and O-glycans contained high levels of fucose and include stage-specific structures. These glycan structures identified in S. mansoni secretions are potentially antigenic motifs and ligands for carbohydrate-binding proteins of the host immune system