Fernandes Maria Cecília, L'Abbate Carolina, Kindro Andreoli Walter, Mortara Renato Arruda
Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo-Escola Paulista de Medicina, Rua Botucatu, 862, 6 andar, São Paulo, SP 04023-062, Brazil.
Microb Pathog. 2007 Jul;43(1):22-36. doi: 10.1016/j.micpath.2007.02.005. Epub 2007 Mar 12.
Previous studies have shown that Coxiella burnetii, an intracellular bacterium that resides within acidified vacuoles with secondary lysosomal characteristics, is an effective modulator of the intracellular traffic of trypomastigote forms of Trypanosoma cruzi. In addition, vacuolar and cellular pH are related to fusion events that result in doubly infected phagosomes. T. cruzi, the etiological agent of Chagas' disease, occurs as different strains grouped in two major phylogenetic lineages: T. cruzi I, associated with the sylvatic cycle, and T. cruzi II, linked to the human disease. In this work we compared extracellular amastigotes (EA), metacyclic trypomastigotes (MT) and tissue culture derived trypomastigotes (TCT) belonging to T. cruzi I or T. cruzi II for their ability to invade and escape from their parasitophorous vacuole (PV), in Vero cells or Vero cells harboring the bacterium, C. burnetti. Distinct invasion patterns were observed between different infective stages and between infective forms of different strains. Studies on the transference kinetics revealed that pH modulates the intracellular traffic of each infective stage, but this influence is not exclusive for each phylogenetic group. Endosomal to lysosomal sequential labeling with EEA-1 and LAMP-1 of the PV formed during the entry of each infective form revealed that the phagosome maturation processes are distinct but not strain-dependent. Due to their low hemolysin and trans-sialidase activities, MTs are retained for longer periods in LAMP-1 positive vacuoles. Our results thus suggest that despite the contrasting invasion capabilities, parasites of distinct phylogenetic group behave in similar fashion once inside the host cell.
先前的研究表明，贝氏柯克斯体是一种寄生于具有次级溶酶体特征的酸化液泡内的胞内细菌，是克氏锥虫无鞭毛体形式细胞内运输的有效调节因子。此外，液泡和细胞的pH值与导致双重感染吞噬体的融合事件有关。恰加斯病的病原体克氏锥虫以不同菌株的形式存在，分为两个主要的系统发育谱系：与野生动物循环相关的克氏锥虫I型，以及与人类疾病相关的克氏锥虫II型。在这项研究中，我们比较了属于克氏锥虫I型或II型的细胞外无鞭毛体（EA）、循环后期锥鞭毛体（MT）和组织培养来源的锥鞭毛体（TCT）在Vero细胞或携带贝氏柯克斯体细菌的Vero细胞中侵入其寄生泡（PV）并从中逸出的能力。在不同感染阶段之间以及不同菌株的感染形式之间观察到了不同的侵入模式。对转运动力学的研究表明，pH值调节每个感染阶段的细胞内运输，但这种影响并非每个系统发育组所特有。用EEA-1和LAMP-1对每种感染形式进入过程中形成的PV进行内体到溶酶体的顺序标记，结果表明吞噬体成熟过程各不相同，但不依赖于菌株。由于MTs的溶血素和转唾液酸酶活性较低，它们在LAMP-1阳性液泡中保留的时间更长。因此，我们的结果表明，尽管侵入能力存在差异，但不同系统发育组的寄生虫一旦进入宿主细胞，其行为方式相似。
