Greub Gilbert, Mege Jean-Louis, Gorvel Jean-Pierre, Raoult Didier, Méresse Stéphane
Institute of Microbiology, Faculty of Biology and Medicine, University of Lausanne, Switzerland.
Cell Microbiol. 2005 Apr;7(4):581-9. doi: 10.1111/j.1462-5822.2004.00488.x.
Parachlamydia acanthamoebae is an obligate intracellular bacterium that naturally infects free-living amoebae. It is a potential agent of pneumonia that resists destruction by human macrophages. However, the strategy used by this Chlamydia-like organism in order to resist to macrophage destruction is unknown. We analysed the intracellular trafficking of P. acanthamoebae within monocyte-derived macrophages. Infected cells were immunolabelled for the bacteria and for various intracellular compartments by using specific antibodies. We analysed the bacteria colocalization with the different subcellular compartments by using epifluorescence and confocal microscopy. Bacterial replication took place 4-6 h post infection within acidic vacuoles. At that time, P. acanthamoebae colocalized with Lamp-1, a membrane marker of late endosomal and lysosomal compartments. A transient accumulation of EEA1 15 min post infection, and of rab7 and the mannose 6-phosphate receptor 30 min post infection confirmed that P. acanthamoebae traffic through the endocytic pathway. The acquisition of Lamp-1 was not different after infection with living and heat-inactivated bacteria. However, 24.5% and 79.5% of living and heat-inactivated P. acanthamoebae, respectively, colocalized with the vacuolar proton ATPase. Moreover, P. acanthamoebae did not colocalized with cathepsin D, a lysosomal hydrolase, suggesting that P. acanthamoebae interferes with maturation of its vacuole. Thus, P. acanthamoebae survives to destruction by human macrophages probably by controlling the vacuole biogenesis.
棘阿米巴嗜衣原体是一种专性细胞内细菌，可自然感染自由生活的阿米巴。它是一种潜在的肺炎病原体，能抵抗人类巨噬细胞的破坏。然而，这种衣原体样生物体用于抵抗巨噬细胞破坏的策略尚不清楚。我们分析了棘阿米巴嗜衣原体在单核细胞衍生巨噬细胞内的细胞内运输情况。通过使用特异性抗体，对感染细胞中的细菌和各种细胞内区室进行免疫标记。我们利用落射荧光显微镜和共聚焦显微镜分析细菌与不同亚细胞区室的共定位情况。感染后4 - 6小时，细菌在酸性液泡内进行复制。此时，棘阿米巴嗜衣原体与Lamp - 1共定位，Lamp - 1是晚期内体和溶酶体区室的膜标记物。感染后15分钟EEA1的短暂积累，以及感染后30分钟rab7和甘露糖6 - 磷酸受体的短暂积累，证实棘阿米巴嗜衣原体通过内吞途径运输。感染活细菌和热灭活细菌后，Lamp - 1的获得情况没有差异。然而，分别有24.5%的活棘阿米巴嗜衣原体和79.5%的热灭活棘阿米巴嗜衣原体与液泡质子ATP酶共定位。此外，棘阿米巴嗜衣原体与溶酶体水解酶组织蛋白酶D没有共定位，这表明棘阿米巴嗜衣原体干扰其液泡的成熟。因此，棘阿米巴嗜衣原体可能通过控制液泡生物发生来在人类巨噬细胞的破坏中存活下来。
