Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea.
Korea Research Institute of Chemical Technology, Daejeon, Republic of Korea.
Vet Res. 2018 Sep 17;49(1):92. doi: 10.1186/s13567-018-0584-0.
Caliciviruses in the genus Sapovirus are a significant cause of viral gastroenteritis in humans and animals. However, the mechanism of their entry into cells is not well characterized. Here, we determined the entry mechanism of porcine sapovirus (PSaV) strain Cowden into permissive LLC-PK cells. The inhibition of clathrin-mediated endocytosis using chlorpromazine, siRNAs, and a dominant negative (DN) mutant blocked entry and infection of PSaV Cowden strain, confirming a role for clathrin-mediated internalization. Entry and infection were also inhibited by the cholesterol-sequestering drug methyl-β-cyclodextrin and was restored by the addition of soluble cholesterol, indicating that cholesterol also contributes to entry and infection of this strain. Furthermore, the inhibition of dynamin GTPase activity by dynasore, siRNA depletion of dynamin II, or overexpression of a DN mutant of dynamin II reduced the entry and infection, suggesting that dynamin mediates the fission and detachment of clathrin- and cholesterol-pits for entry of this strain. In contrast, the inhibition of caveolae-mediated endocytosis using nystatin, siRNAs, or a DN mutant had no inhibitory effect on entry and infection of this strain. It was further determined that cell entry of PSaV Cowden strain required actin rearrangements for vesicle internalization, endosomal trafficking from early to late endosomes through microtubules, and late endosomal acidification for uncoating. We conclude that PSaV strain Cowden is internalized into LLC-PK cells by clathrin- and cholesterol-mediated endocytosis that requires dynamin II and actin rearrangement, and that the uncoating occurs in the acidified late endosomes after trafficking from the early endosomes through microtubules.
杯状病毒属的札幌病毒是导致人和动物病毒性肠胃炎的重要病原体。然而,其进入细胞的机制尚未得到很好的描述。在这里,我们确定了猪札幌病毒(PSaV)Cowden 株进入许可的 LLC-PK 细胞的进入机制。用氯丙嗪、siRNA 和显性负突变(DN 突变)抑制网格蛋白介导的内吞作用,阻断了 PSaV Cowden 株的进入和感染,证实了网格蛋白介导的内化作用。胆固醇隔离药物甲基-β-环糊精和添加可溶胆固醇也抑制了进入和感染,表明胆固醇也有助于该株的进入和感染。此外,通过 dynasore 抑制动力蛋白 GTP 酶活性、siRNA 耗尽动力蛋白 II 或过表达动力蛋白 II 的 DN 突变体,减少了进入和感染,表明动力蛋白介导了该株的裂合和脱离网格蛋白和胆固醇陷窝进入。相比之下,使用制霉菌素抑制小窝蛋白介导的内吞作用、siRNA 或 DN 突变体对该株的进入和感染没有抑制作用。进一步确定 PSaV Cowden 株的细胞进入需要肌动蛋白重排进行囊泡内化、通过微管从早期内体到晚期内体的内体运输以及晚期内体酸化进行脱壳。我们得出结论,PSaV Cowden 株通过网格蛋白和胆固醇介导的内吞作用进入 LLC-PK 细胞,该作用需要 dynamin II 和肌动蛋白重排,并且脱壳发生在微管运输后从早期内体到晚期内体酸化后。
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