Department of Medical Microbiology and Infection Prevention, University Medical Center Groningen, University of Groningen, The Netherlands.
PLoS Negl Trop Dis. 2020 Aug 7;14(8):e0008469. doi: 10.1371/journal.pntd.0008469. eCollection 2020 Aug.
Chikungunya virus (CHIKV) is a re-emerging mosquito-borne alphavirus, which has rapidly spread around the globe thereby causing millions of infections. CHIKV is an enveloped virus belonging to the Togaviridae family and enters its host cell primarily via clathrin-mediated endocytosis. Upon internalization, the endocytic vesicle containing the virus particle moves through the cell and delivers the virus to early endosomes where membrane fusion is observed. Thereafter, the nucleocapsid dissociates and the viral RNA is translated into proteins. In this study, we examined the importance of the microtubule network during the early steps of infection and dissected the intracellular trafficking behavior of CHIKV particles during cell entry. We observed two distinct CHIKV intracellular trafficking patterns prior to membrane hemifusion. Whereas half of the CHIKV virions remained static during cell entry and fused in the cell periphery, the other half showed fast-directed microtubule-dependent movement prior to delivery to Rab5-positive early endosomes and predominantly fused in the perinuclear region of the cell. Disruption of the microtubule network reduced the number of infected cells. At these conditions, membrane hemifusion activity was not affected yet fusion was restricted to the cell periphery. Furthermore, follow-up experiments revealed that disruption of the microtubule network impairs the delivery of the viral genome to the cell cytosol. We therefore hypothesize that microtubules may direct the particle to a cellular location that is beneficial for establishing infection or aids in nucleocapsid uncoating.
基孔肯雅病毒（CHIKV）是一种重新出现的蚊媒甲病毒，已迅速在全球范围内传播，从而导致数百万人感染。CHIKV 是一种包膜病毒，属于披膜病毒科，主要通过网格蛋白介导的内吞作用进入宿主细胞。内吞后，含有病毒颗粒的内吞小泡通过细胞移动，并将病毒递送至早期内体，在那里观察到膜融合。此后，核衣壳解离，病毒 RNA 被翻译成蛋白质。在这项研究中，我们研究了微管网络在感染早期步骤中的重要性，并剖析了 CHIKV 颗粒在细胞进入过程中的细胞内运输行为。在膜半融合之前，我们观察到两种截然不同的 CHIKV 细胞内运输模式。在细胞进入过程中，一半的 CHIKV 病毒颗粒保持静止并在细胞边缘融合，而另一半则在递送至 Rab5 阳性早期内体之前表现出快速定向的微管依赖性运动，并主要在细胞的核周区域融合。微管网络的破坏减少了感染细胞的数量。在这些条件下，膜半融合活性不受影响，但融合仅限于细胞边缘。此外，后续实验表明，微管网络的破坏会损害病毒基因组向细胞质的传递。因此，我们假设微管可能将颗粒引导到有利于建立感染或有助于核衣壳脱壳的细胞位置。
