Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.
Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, The Chinese Academy of Agricultural Sciences, Maduan Street 427, Harbin 150001, China.
Viruses. 2018 Oct 15;10(10):562. doi: 10.3390/v10100562.
Porcine circovirus type 2 (PCV2) is associated with various diseases which are designated as PCV2-associated diseases (PCVADs). Their severity varies among breeds. In the diseased pigs, virus is present in monocytes, without replication or full degradation. PCV2 entry and viral outcome in primary porcine monocytes and the role of monocytes in PCV2 genetic susceptibility have not been studied. Here, virus uptake and trafficking were analyzed and compared among purebreds Piétrain, Landrace and Large White and hybrid Piétrain × Topigs20. Viral capsids were rapidly internalized into monocytes, followed by a slow disintegration to a residual level. PCV2 uptake was decreased by chlorpromazine, cytochalasin D and dynasore. The internalized capsids followed the endosomal trafficking pathway, ending up in lysosomes. PCV2 genome was nicked by lysosomal DNase II in vitro, but persisted in monocytes in vivo. Monocytes from purebred Piétrain and the hybrid showed a higher level of PCV2 uptake and disintegration, compared to those from Landrace and Large White. In conclusion, PCV2 entry occurs via clathrin-mediated endocytosis. After entry, viral capsids are partially disintegrated, while viral genomes largely escape from the pathway to avoid degradation. The degree of PCV2 uptake and disintegration differ among pig breeds.
猪圆环病毒 2 型（PCV2）与各种疾病相关，这些疾病被称为 PCV2 相关疾病（PCVADs）。它们的严重程度因品种而异。在患病猪中，病毒存在于单核细胞中，没有复制或完全降解。PCV2 在原代猪单核细胞中的进入和病毒结局以及单核细胞在 PCV2 遗传易感性中的作用尚未研究。在这里，分析和比较了纯种皮特兰猪、长白猪和大白猪以及皮特兰×托佩格斯 20 杂交猪的病毒摄取和转运。病毒衣壳迅速被单核细胞内化，随后缓慢崩解至残留水平。氯丙嗪、细胞松弛素 D 和 dynasore 可降低 PCV2 的摄取。内化的衣壳沿着内体转运途径，最终进入溶酶体。PCV2 基因组在体外被溶酶体 DNase II 切割，但在体内仍存在于单核细胞中。与来自长白猪和大白猪的单核细胞相比，来自纯种皮特兰猪和杂交猪的单核细胞显示出更高水平的 PCV2 摄取和崩解。总之，PCV2 通过网格蛋白介导的内吞作用进入。进入后，病毒衣壳部分崩解，而病毒基因组则很大程度上逃避该途径以避免降解。猪品种之间的 PCV2 摄取和崩解程度不同。
