Department of Infectomics and Molecular Pathogenesis, Center for Research and Advanced Studies, 07360, Mexico, DF, Mexico.
Parasitol Res. 2012 Jul;111(1):215-21. doi: 10.1007/s00436-012-2820-2. Epub 2012 Jan 26.
The rapid redistribution of surface antigen-antibody complexes in trophozoites of the human protozoan parasite Entamoeba histolytica, in a process known as capping, has been considered as a means of the parasite to evade the host immune response. So far, capping has been documented in the invasive E. histolytica, whereas the mobility of surface components in the non-invasive Entamoeba dispar is not known. E. dispar does not induce liver lesions in rodent experimental models, in contrast to the liver abscesses produced by E. histolytica in the same animal model. We have therefore analyzed the mobility of surface receptors to the lectin concanavalin A and of Rab11, a membrane-associated protein, in both species of Entamoebae by confocal fluorescence microscopy and transmission and scanning electron microscopy. The great majority of E. histolytica trophozoites became morphologically polarized through the formation of well-defined caps at the posterior pole of the parasite. Actin colocalized with the lectin caps. Antibodies against the membrane protein Rab 11 also produced capping. In striking contrast, in E. dispar, the mobility of concanavalin A surface receptors was restricted to the formation of irregular surface patches that did no progress to constitute well-defined caps. Also, anti-Rab 11 antibodies did not result in capping in E. dispar. Whether the failure of E. dispar to efficiently mobilize surface molecules in response to lectin or antibodies as shown in the present results is related to its non-invasive character represents an interesting hypothesis requiring further analysis.
在人类原生动物寄生虫溶组织内阿米巴滋养体中，表面抗原-抗体复合物的快速再分布，这一过程被称为“盖帽”，被认为是寄生虫逃避宿主免疫反应的一种方式。到目前为止，已经在侵袭性的溶组织内阿米巴中记录了盖帽，而非侵袭性的迪斯帕内阿米巴表面成分的流动性尚不清楚。迪斯帕内阿米巴在啮齿动物实验模型中不会引起肝损伤，而溶组织内阿米巴在同一动物模型中会产生肝脓肿。因此，我们通过共聚焦荧光显微镜和透射电子显微镜及扫描电子显微镜分析了两种内阿米巴表面受体对凝集素伴刀豆球蛋白 A 和膜相关蛋白 Rab11 的流动性。绝大多数溶组织内阿米巴滋养体通过在寄生虫后极形成明确的帽状结构而发生形态极化。肌动蛋白与凝集素帽共定位。针对膜蛋白 Rab11 的抗体也产生了盖帽。与此形成鲜明对比的是，在迪斯帕内阿米巴中，伴刀豆球蛋白 A 表面受体的流动性仅限于形成不规则的表面斑块，而不会形成明确的帽状结构。此外，抗 Rab11 抗体在迪斯帕内阿米巴中也不会导致盖帽。迪斯帕内阿米巴未能有效地动员表面分子以响应凝集素或抗体，如本研究结果所示，这与其非侵袭性特征有关，这是一个有趣的假说，需要进一步分析。
