College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu Province, China.
Autophagy. 2012 Oct;8(10):1434-47. doi: 10.4161/auto.21159. Epub 2012 Jun 28.
An increasing number of studies demonstrate that autophagy, an intrinsic mechanism that can degrade cytoplasmic components, is involved in the infection processes of a variety of pathogens. It can be hijacked by various viruses to facilitate their replication. In this study, we found that PRRSV infection significantly increases the number of double- or single-membrane vesicles in the cytoplasm of host cells in ultrastructural analysis. Our results showed the LC3-I was converted into LC3-II after virus infection, suggesting the autophagy machinery was activated. We further used pharmacological agents and shRNAs to confirm that autophagy promoted the replication of PRRSV in host cells. Confocal microscopy analysis showed that PRRSV inhibited the fusion between autophagosomes and lysosomes, suggesting that PRRSV induced incomplete autophagy. This suppression caused the accumulation of autophagosomes which may serve as replication site to enhance PRRSV replication. It has been shown that NSP2 and NSP3 of arterivirus are two components of virus replication complex. We also found in our studies that NSP2 colocalized with LC3 in MARC-145 cells by performing confocal microscopy analysis and continuous density gradient centrifugation. Our studies presented here indicated that autophagy was activated during PRRSV infection and enhanced PRRSV replication in host cells by preventing autophagosome and lysosome fusion.
越来越多的研究表明，自噬是一种可以降解细胞质成分的内在机制，参与了多种病原体的感染过程。它可以被各种病毒劫持，以促进其复制。在这项研究中，我们发现，在超微结构分析中，PRRSV 感染显著增加了宿主细胞细胞质中双层或单层囊泡的数量。我们的结果表明，LC3-I 在病毒感染后转化为 LC3-II，表明自噬机制被激活。我们进一步使用药理学试剂和 shRNA 来确认自噬促进了 PRRSV 在宿主细胞中的复制。共聚焦显微镜分析表明，PRRSV 抑制了自噬体与溶酶体之间的融合，表明 PRRSV 诱导了不完全自噬。这种抑制导致自噬体的积累，可能作为复制位点增强 PRRSV 复制。已经表明，动脉病毒的 NSP2 和 NSP3 是病毒复制复合物的两个组成部分。通过共聚焦显微镜分析和连续密度梯度离心，我们还发现 NSP2 在 MARC-145 细胞中与 LC3 共定位。我们的研究表明，自噬在 PRRSV 感染过程中被激活，并通过阻止自噬体和溶酶体融合来增强宿主细胞中的 PRRSV 复制。
