Parasitology Department, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, 28222, Spain.
Electronic and Confocal Microscopy Department, Unidades Comunes Científico-Técnicas (SG-SAFI), Instituto de Salud Carlos III, Madrid, 28222, Spain.
Sci Rep. 2018 Sep 20;8(1):14116. doi: 10.1038/s41598-018-32349-7.
Based on confocal fluorescence and bright field video microscopy, we present detailed observations on the processes of invasion and egress of erythrocytes by the apicomplexan parasite Babesia divergens. Time-lapse images reveal numerous unexpected findings associated with the dynamics of B. divergens and its ability to manipulate the erythrocyte during both processes in its asexual cycle under in vitro conditions. Despite the speed at which these processes occur and the small size of the parasite, we capture infective merozoites moving vigorously and causing striking deformations in the erythrocyte's plasma membrane during an active invasion. We also observed intraerythrocytic dynamic stages as paired pyriforms, double paired pyriforms, tetrads, unattached pyriform sister cells and multiple parasite stages resulting in the release of large numbers of merozoites over a short period. Of considerable interest is that time-lapse images reveal a novel mechanism of egress used by B. divergens to exit the human erythrocyte. The release occurs when B. divergens parasites establish contacts with the plasma membrane of the erythrocyte from within, before exiting the cell. Visualization and analysis of the images enabled us to obtain useful information and broaden our knowledge of complex and crucial events involved with parasitisation of human erythrocytes by B. divergens.
基于共聚焦荧光和明场视频显微镜，我们对锥体虫属寄生虫巴贝西虫入侵和逸出红细胞的过程进行了详细观察。延时图像揭示了许多与 B. divergens 的动力学及其在体外条件下无性周期这两个过程中操纵红细胞的能力相关的意外发现。尽管这些过程发生的速度很快，而且寄生虫的体积很小，但我们还是捕捉到了处于活跃入侵状态下快速移动的感染性裂殖子，导致红细胞质膜发生明显变形。我们还观察到了红细胞内的动态阶段，如成对的梨形虫、双成对的梨形虫、四联体、未附着的梨形姐妹细胞和多个导致大量裂殖子在短时间内释放的寄生虫阶段。引人注目的是，延时图像揭示了 B. divergens 用于从内部离开人类红细胞的一种新的逸出机制。当 B. divergens 寄生虫从内部与红细胞的质膜建立联系后，就会发生释放，然后再离开细胞。对图像的可视化和分析使我们能够获得有用的信息，并拓宽我们对 B. divergens 寄生人类红细胞所涉及的复杂和关键事件的认识。
