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首页> 外文期刊>Infection and immunity >Early Events in Phagosome Establishment Are Required for Intracellular Survival of Legionella pneumophila
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Early Events in Phagosome Establishment Are Required for Intracellular Survival of Legionella pneumophila

机译：嗜肺军团菌细胞内存活需要在吞噬体建立中的早期事件。

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During infection, the Legionnaires’ disease bacterium,Legionella pneumophila, survives and multiplies within a specialized phagosome that is near neutral pH and does not fuse with host lysosomes. In order to understand the molecular basis of this organism’s ability to control its intracellular fate, we have isolated and characterized a group of transposon-generated mutants which were unable to kill macrophages and were subsequently found to be defective in intracellular multiplication. These mutations define a set of 20 genes (19 icm [for intracellular multiplication] genes and dotA [for defect in organelle trafficking]). In this report, we describe a quantitative assay for phagosome-lysosome fusion (PLF) and its use to measure the levels of PLF in cells that have been infected with either wild-type L. pneumophila or one of several mutants defective in different icm genes ordotA. By using quantitative confocal fluorescence microscopy, PLF could be scored on a per-bacterium basis by determining the extent to which fluorescein-labeled L. pneumophilacolocalized with host lysosomes prelabeled with rhodamine-dextran. Remarkably, mutations in the six genes that were studied resulted in maximal levels of PLF as quickly as 30 min following infection. These results indicate that several, and possibly all, of the icmand dotA gene products act at an early step during phagosome establishment to determine whether L. pneumophila-containing phagosomes will fuse with lysosomes. Although not ruled out, subsequent activity of these gene products may not be necessary for successful intracellular replication.
机译：在感染过程中，军团菌病菌嗜肺军团菌（Legionella pneumophila）可在接近中性pH且不与宿主溶酶体融合的特化吞噬体内存活并繁殖。为了了解这种生物控制其细胞内命运的分子基础，我们分离并鉴定了一组由转座子产生的突变体，它们不能杀死巨噬细胞，随后被发现在细胞内增殖中存在缺陷。这些突变定义了一组20个基因（19个 icm [用于细胞内繁殖]基因和 dotA [用于细胞器运输缺陷]）。在本报告中，我们描述了吞噬体-溶酶体融合（PLF）的定量测​​定法及其用于测量已被野生型 L感染的细胞中PLF的水平。肺炎或几种不同的 icm 基因或 dotA 有缺陷的突变体之一。通过使用定量共聚焦荧光显微镜，可以通过确定荧光素标记的 L的程度在每个细菌的基础上对PLF进行评分。肺炎衣原体与用若丹明-葡聚糖预先标记的宿主溶酶体共定位。值得注意的是，所研究的六个基因中的突变导致感染后30分钟内PLF的最高水平。这些结果表明， icm 和 dotA 基因产物中的几种，甚至全部可能在吞噬体建立过程的早期阶段起作用，以确定是否为 L。含有肺炎球菌的吞噬体会与溶酶体融合。尽管不排除这些基因产物的后续活性对于成功的细胞内复制可能不是必需的。

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