DIFFERENTIATION OF LEISHMANIA PROMASTIGOTES

利什曼原虫前鞭毛体的分化

• 批准号: 3809590
• 负责人: D L SACKS
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3809590
• 关键词: Coleoptera; Leishmania; Leishmania donovani; carbohydrate structure; complement pathway; complement receptor; glycolipids; immunoelectron microscopy; intracellular parasitism; lectin; leishmaniasis; life cycle; macrophage; microorganism culture; microorganism growth; opsonin; protozoal antigen; surface antigens

During growth within the sand fly and within axenic culture, Leishmania promastigotes undergo differentiation from a non-infective to an infective or metacyclic stage which is uniquely adapted for life in the vertebrate. For some species of Leishmania (L. donovani and L. major) this development is accompanied by a substantial modification of the surface lipophosphoglycan (LPG) which is the major surface glycoconjugate of these cells. During metacyclogenesis, the LPG is developmentally modified such that it no longer binds the lectin PNA, it expresses a novel carbohydrate epitope, and the number of phosphorylated saccharide units expressed increases 2-3 fold. Immunogold labeling of the surface LPG revealed a 10nm thickening in the LPG coat, which assumed a filamentous appearance on freeze-fracture preparations. The LPG on Old Word promastigotes forms a densely packed surface coat which effectively masks other surface molecules, such as GP63. We have presented evidence that the elongation of the LPG serves to promote the complement resistance of inoculated metacyclics by preventing insertion of the membrane attack complex into the membrane. LPG does not appear to be expressed on the surface of L. major L. donovani amastigotes, suggesting that the surface coat is a stage specific structure which undoubtedly influences the survival and behavior of the parasite within the alimentary tract of the sand fly. These vector biological studies have only recently been initiated. LPG has also been investigated on New World species, and while metacyclic promastigotes of these species express saccharide units which are altered in composition, there is no elongation of the LPG, and this is consistent with the continued serum susceptibility of these infective forms.

在白蛉和无菌培养物中生长期间，利什曼原虫 前鞭毛体经历从非感染性到感染性的分化 或专为脊椎动物的生活所适应的元周期阶段。 利什曼原虫（L. donovani和L.（主要）这一发展 伴随着表面的实质性改变 脂磷酸聚糖（LPG），其是这些蛋白的主要表面糖缀合物， 细胞 在准气旋生成过程中，液化石油气发生了发展性的变化， 它不再结合凝集素PNA，它表达了一种新的碳水化合物， 表位和表达的磷酸化糖单位的数量 增加2-3倍。 免疫胶体金标记的LPG表面显示10 nm的 在LPG涂层中增厚，其呈现丝状外观， 冷冻断裂准备。 旧词promastigotes上的LPG形成一个 致密的表面涂层，有效地掩盖了其他表面 分子，如GP 63。 我们提出的证据表明， LPG用于促进接种的补体抵抗， 通过防止膜攻击复合物插入到 膜的 LPG似乎不表达在L的表面上。主要 L. donovani无鞭毛体，表明表面涂层是一个阶段 特定的结构，这无疑会影响生存和行为 白蛉消化道内的寄生虫。 这些载体 生物学研究最近才开始。 LPG也是 调查新世界物种，而metacyclic promastigotes的 这些种类表达组成改变的糖单元， LPG没有伸长，这与 这些感染形式的持续血清易感性。