CHITINASE SECRETED BY LEISHMANIA FUNCTIONS IN THE SANDFLY VECTOR
CHITINASE SECRETED BY LEISHMANIA FUNCTIONS IN THE SANDFLY VECTOR
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DOI：
10.1098/rspb.1991.0097
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发表时间：
1991-08-22
影响因子：
4.7
通讯作者：
SHLOMAI, J
中科院分区：
文献类型：
--
作者：
SCHLEIN, Y;JACOBSON, RL;SHLOMAI, J
利什曼原虫主要寄生虫被白蛉白蛉摄入宿主血液后在围食膜内繁殖。该膜由几丁质框架和蛋白质碳水化合物基质组成，由昆虫中肠分泌在食物周围。受感染果蝇的组织学切片显示，围营养膜前部区域的几丁质层裂解，使得大量寄生虫能够向前迁移。这种分解的位置和性质都是受感染苍蝇所特有的。在后期，寄生虫集中在心脏瓣膜区域，随后前肠的这一部分失去其角质层。我们发现几丁质酶和N-乙酰氨基葡萄糖苷酶是由培养的大型乳杆菌前鞭毛体分泌的，但不是由白蛉内脏分泌的。因此，寄生虫的这些酶可以催化围食膜几丁质层的裂解。在其他锥虫动物中也观察到了这两种酶的活性，包括杜氏锥虫、婴儿锥虫、巴西锥虫、塞摩利细单胞菌、束状短膜虫和路易斯锥虫。
Leishmania major parasites ingested with host blood by the sandfly Phlebotomus papatasi multiply confined within the peritrophic membrane. This membrane consists of a chitin framework and a protein carbohydrate matrix and it is secreted around the food by the insect midgut. Histological sections of infected flies show lysis of the chitin layer in the anterior region of the peritrophic membrane that permits the essential forward migration of a concentrated mass of parasites. Both the location and the nature of this disintegration are specific to infected flies. At a later stage the parasites concentrate in the cardiac valve region and subsequently this segment of the fore gut loses its cuticular lining. We have found that chitinase and N-acetylglucosaminidase are secreted by cultured L. major promastigotes, but not by sandfly guts. Hence lysis of the chitin layer of the peritrophic membrane could be catalysed by these enzymes of the parasites. Activity of both enzymes was also observed in other trypanosomatids, including L. donovani, L. infantum, L. braziliensis, Leptomonas seymouri, Crithidia fasciculata and Trypanosoma lewisi.