Laboratório de Ultraestrutura Celular Hertha Meyer, Centro de Pesquisa em Medicina de Precisão, Instituto de Biofísica Carlos Chagas Filho/Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Laboratório de Ultraestrutura Celular Hertha Meyer, Centro de Pesquisa em Medicina de Precisão, Instituto de Biofísica Carlos Chagas Filho/Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem - INBEB, and Centro Nacional de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Centro de Estudos Biomédicos-CMABio, Escola Superior de Saúde, Universidade do Estado do Amazonas, Manaus, Amazonas, Brazil.
Vet Parasitol. 2023 Oct;322:110006. doi: 10.1016/j.vetpar.2023.110006. Epub 2023 Aug 10.
Toxoplasma gondii is an obligate intracellular protozoan of worldwide distribution. It is effective in the infection of various homoeothermic animals of economic importance. The process of T. gondii invasion of host cells occurs in less than 20 s by the active mechanism of penetration. First, a mobile junction is formed due to the association between the apical end of the parasite and the host cell surface. Then, the secretion of invasive and docking proteins allows the formation of the mobile junction before the complete internalization of the parasite. Here, using high-resolution microscopy, it was described new morphological observations of the early events of host cell invasion by tachyzoites of T. gondii. Attempts were made to synchronize the interaction process using low temperatures and treatment of the host cells with cytochalasin D, a drug that interferes with the actin dynamics. Images were obtained showing that the parasite and the host cells seem to release small vesicles with diameters varying from 25 to 100 nm. Furthermore, tunneling nanotubes emerge from the host cell surface and interact with the parasite even at long distance. These observations add new details of adhesion and entry events, such as surface projections of the host cell plasma membrane, pseudopods, and nanotubes radiating from the host cell toward the parasite. In addition, scanning microscopy revealed intense vesiculation, with a morphological characteristic of extracellular microvesicles, during the entry of the tachyzoite into the host cell.
刚地弓形虫是一种全球性分布的专性细胞内原生动物，能够有效感染各种具有经济重要性的恒温动物。刚地弓形虫入侵宿主细胞的过程通过主动穿透机制在不到 20 秒内完成。首先，寄生虫的顶端与宿主细胞表面之间的关联形成一个移动连接点。然后，入侵和对接蛋白的分泌允许在寄生虫完全内化之前形成移动连接点。在这里，使用高分辨率显微镜，描述了速殖子入侵宿主细胞的早期事件的新形态学观察。尝试使用低温和细胞松弛素 D 处理宿主细胞来同步相互作用过程，细胞松弛素 D 是一种干扰肌动蛋白动态的药物。获得的图像表明，寄生虫和宿主细胞似乎释放出直径在 25 至 100nm 之间的小泡。此外，即使在远距离，从宿主细胞表面伸出的隧道纳米管也会与寄生虫相互作用。这些观察结果增加了粘附和进入事件的新细节，例如宿主细胞膜质的表面突起、伪足和从宿主细胞向寄生虫辐射的纳米管。此外，扫描显微镜显示，在速殖子进入宿主细胞的过程中，发生强烈的囊泡化，具有细胞外微泡的形态特征。
