Department of Veterinary Parasitology, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
The United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
Sci Rep. 2017 Jul 18;7(1):5675. doi: 10.1038/s41598-017-05956-z.
Intracellular pathogens have numerous strategies for effective dissemination within the host. Many intracellular pathogens first infect leukocytes, which they use as a vehicle to transport them to target organs. Once at the target organ, intracellular parasite Toxoplasma gondii can cross the capillary wall in extracellular form by infecting endothelial cells. However, after egression from leukocytes, extracellular parasites face the risk of host immune attack. In this study, observation of infected mouse organs, using a method that renders tissue transparent, revealed that adhesion of tachyzoite-infected leukocytes to endothelial cells triggers immediate egression of the parasite. This signal enables the parasite to time egression from its vehicle leukocyte to coincide with arrival at a target organ, minimizing the opportunity for immune attack during the transition from a vehicle leukocyte to capillary endothelial cells.
细胞内病原体有许多有效的传播策略在宿主内传播。许多细胞内病原体首先感染白细胞，然后利用白细胞作为载体将其运输到靶器官。一旦到达靶器官，细胞内寄生虫刚地弓形虫可以通过感染内皮细胞以细胞外形式穿过毛细血管壁。然而，在从白细胞中逸出后，细胞外寄生虫面临着宿主免疫攻击的风险。在这项研究中，使用一种使组织透明的方法观察感染小鼠的器官，发现被速殖子感染的白细胞与内皮细胞的黏附会立即引发寄生虫的逸出。这种信号使寄生虫能够及时从其载体白细胞逸出，与到达靶器官的时间相吻合，从而最大限度地减少从载体白细胞到毛细血管内皮细胞的转变过程中免疫攻击的机会。
