DEVELOPMENTAL BIOLOGY OF LEISHMANIA PROMASTIGOTES

在白蛉和无菌培养物中生长期间，利什曼原虫 前鞭毛体经历从分裂的非感染阶段 静止感染或代谢循环阶段，其独特地适于 脊椎动物的生命 培养条件促进 现在已经优化了寄生虫到感染阶段的分化 对于各种菌株。 这一发展伴随着一个巨大的 修饰表面脂磷酸聚糖（LPG），这是主要的 这些细胞的表面糖缀合物。 发育性的改变 包括 一个 伸长率 的 分子由于2-3倍 磷酸化的数量增加 低聚糖化的 单位表示，并在一些组成的变化， 这些单位。 在L. major和L. Donovani结构 多态性表示为末端半乳糖残基的丢失， 液化石油气 L的相关结构变化现已得到证实。 amazonensis和L.婴儿 末端的取代或加帽 暴露的糖与其他糖残基被证明是分子 前鞭毛体附着和释放的机制 中肠上皮细胞在其发展过程中的苍蝇。 具体 现已鉴定出介导结合的寡糖单元。 这些末端糖的物种特异性似乎影响了它们的生物学特性。 在自然界中观察到的媒介能力的种特异性。 石油气 已成功地用于探测沙子中的凝集素样受体 苍蝇肠 在相关研究中，发现抗LPG的存在 感染性血粉中的抗体抑制了 沙蝇中肠内的传染性感染。 这种抑制 只有在血粉中含有抗利什曼原虫药时 慢性感染血清中存在的抗体。

During growth within the sand fly and within axenic culture, Leishmania promastigotes undergo differentiation from a dividing non-infective stage to a resting infective or metacyclic stage which is uniquely adapted for life in the vertebrate. The culture conditions which promote differentiation of parasites to an infective stage have now been optimized for various strains. This development is accompanied by a substantial modification of the surface lipophosphoglycan (LPG) which is the major surface glycoconjugate of these cells. The developmental modifications include an elongation of the molecule due to a 2-3 fold increase in the number of phosphorylated oligosaccharated units expressed, and a change in the composition of some of these units. In the case of L. major and L. donovani the structural polymorphism is expressed as a loss of terminal galactose residues on the LPG. Related structural changes have now been confirmed for L. amazonensis and L. infantum. The substitution or capping of terminally exposed sugars with other sugar residues was shown to be the molecular mechnism underlying the attachment and release of promastigotes from midgut epithelial cells during their development in the fly. The specific oligosaccharide units which mediate the binding have now been identified. The species specificity of these terminal sugars appears to influence the species specificity of vectorial capacity observed in nature. LPG has been successfully used to probe for the lectin like receptors in the sand fly gut. In related studies, it was found that the presence of anti-LPG antibodies within an infective bloodmeal inhibited the development of transmissible infections within the sand fly midgut. This inhibition was only apparent when the bloodmeal also contained anti-leishmanial antibodies present in chronic infection sera.