DEVELOPMENTAL BIOLOGY OF LEISHMANIA PROMASTIGOTES

在沙蝇体内和无菌体内生长期间，利什曼原虫 前鞭毛体经历从分裂的非感染阶段的分化 到静息感染或后循环阶段，这一阶段特别适合于 脊椎动物的生命。伴随这一发展的是一项实质性的 主要的表面脂多糖(LPG)的改性 这些细胞的表面糖偶联物。在L.梅杰和L. 杜诺瓦尼前鞭毛体培养衍生的结构多态 表示为液化石油气上末端半乳糖残基的损失。vbl.使用 抗主要乳杆菌LPG的阶段特异性单抗，完全相同 液化石油气的结构变化现在已经被证明是偏循环的。 在自然媒介P.Papatasi中发现，特别是那些 在强迫进食过程中发现从口吻中出现的偏循环 实验。末端暴露的糖的替代或封端 与其他糖和其他糖残留物一起被证明是分子 前鞭毛体附着和释放的机制 苍蝇化生过程中的中肠上皮细胞。这个 这些末端糖的种间多态似乎会影响 在自然界中观察到的媒介能力的物种特异性。因此， 提纯的原环液化石油气的原环前体体能力 各种利什曼原虫与不同种类的中肠上皮细胞结合 沙蝇物种强行预测了媒介能力。

During growth within the sandfly and within axenic, Leishmania promastigotes undergo differentiation from a dividing noninfective stage to a resting infective or metacyclic stage which is uniquely adapted for life in the vertebrate. This development is accompanied by a substantial modification of the surface lipophosphoglycan (LPG) which is the major surface glycoconjugate of these cells. In the case of L. major and L. donovani promastigotes derived from culture, the structural polymorphism is expressed as a loss of terminal galactose residues on the LPG. Using stage specific monoclonal antibodies against L. major LPG, identical structural changes in LPG have now been demonstrated for metacyclics found within the natural vector, P. papatasi, and in particular those metacyclics found to emerge from the proboscis during force feeding experiments. The substitution or capping of terminally exposed sugars with other sugars with other sugar residues was shown to be the molecular mechanism underlying the attachment and release of promastigotes from midgut epithelial cells during metacyclogenesis in the fly. The interspecific polymorphisms of these terminal sugars appears to influence the species specificity of vectorial competence observed in nature. Thus, the ability of procyclic promastigotes of the purified procyclic LPG of various Leishmania species to bind to midgut epithelial cells of various sandfly species forcibly predicts vectorial competence.