State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 1 Xu Jiaping, Lanzhou, 730046, Gansu, China.
College of Animal Husbandry and Veterinary Medicine, Southwest Minzu University, 16 Yihuan Rd., Chengdu, 610041, Sichuan, China.
BMC Vet Res. 2023 Mar 15;19(1):60. doi: 10.1186/s12917-023-03575-7.
Canine distemper virus (CDV) is one of the most contagious and lethal viruses known to the Canidae, with a very broad and expanding host range. Autophagy serves as a fundamental stabilizing response against pathogens, but some viruses have been able to evade or exploit it for their replication. However, the effect of autophagy mechanisms on CDV infection is still unclear.
In the present study, autophagy was induced in CDV-infected Vero cells as demonstrated by elevated LC3-II levels and aggregation of green fluorescent protein (GFP)-LC3 spots. Furthermore, CDV promoted the complete autophagic process, which could be determined by the degradation of p62, co-localization of LC3 with lysosomes, GFP degradation, and accumulation of LC3-II and p62 due to the lysosomal protease inhibitor E64d. In addition, the use of Rapamycin to promote autophagy promoted CDV replication, and the inhibition of autophagy by Wortmannin, Chloroquine and siRNA-ATG5 inhibited CDV replication, revealing that CDV-induced autophagy facilitated virus replication. We also found that UV-inactivated CDV still induced autophagy, and that nucleocapsid (N) protein was able to induce complete autophagy in an mTOR-dependent manner.
This study for the first time revealed that CDV N protein induced complete autophagy to facilitate viral replication.
犬瘟热病毒 (CDV) 是犬科动物中传染性最强、致死率最高的病毒之一，宿主范围非常广泛。自噬作为一种针对病原体的基本稳定反应，但有些病毒能够逃避或利用它进行复制。然而，自噬机制对 CDV 感染的影响尚不清楚。
在本研究中，通过 LC3-II 水平升高和绿色荧光蛋白 (GFP)-LC3 斑点聚集，证实 CDV 感染的 Vero 细胞中诱导了自噬。此外，CDV 促进了完整的自噬过程，这可以通过 p62 的降解、LC3 与溶酶体的共定位、GFP 的降解以及由于溶酶体蛋白酶抑制剂 E64d 导致的 LC3-II 和 p62 的积累来确定。此外，使用 Rapamycin 促进自噬会促进 CDV 复制，而 Wortmannin、Chloroquine 和 siRNA-ATG5 抑制自噬会抑制 CDV 复制，表明 CDV 诱导的自噬促进了病毒复制。我们还发现，UV 灭活的 CDV 仍能诱导自噬，核衣壳 (N) 蛋白能够以 mTOR 依赖的方式诱导完整的自噬。
本研究首次揭示了 CDV N 蛋白诱导完整自噬以促进病毒复制。
