猪丁型冠状病毒诱导的细胞线粒体凋亡

猪丁型冠状病毒(Porcine deltacoronavirus,PDCoV)是一种新型的猪肠道致病性冠状病毒,可引起猪群剧烈腹泻及呕吐,但致病机制尚不清楚。本研究检测了PDCoV感染诱导的细胞凋亡。Caspase酶活性检测显示,在PDCoV感染的细胞中,caspase 3、caspase 8和caspase 9的活性随病毒感染量的增多而显著提高,类似的现象未能在紫外灭活病毒感染的细胞中观察到,表明PDCoV感染可同时激活内源性与外源性细胞凋亡通路,并暗示细胞凋亡的诱导依赖于病毒复制。为深入探究PDCoV诱导的内源性细胞凋亡,分别检测胞浆和线粒体中细胞色素C与凋亡诱导因子。结果显示,与正常细胞相比,PDCoV感染细胞从线粒体释放到胞浆的细胞色素C显著增多,且其释放量随着感染时间的延长而增多,而凋亡诱导因子始终定位于线粒体,提示PDCoV感染通过促使线粒体膜间隙的细胞色素C进入胞浆而启动caspase依赖的线粒体凋亡通路。本研究初步揭示了PDCoV诱导细胞凋亡的机制。

Porcine deltacoronavirus induces mitochondrial apoptosis in ST cells

Porcine deltacoronavirus (PDCoV) is a newly emerging enteropathogenic swine coronavirus causing acute diarrhea and vomiting in pigs. The apoptosis of ST cells induced by PDCoV infection was studied in this research. In ST cells, caspase activity assay showed that the activity of caspase 3, caspase 8 and caspase 9 increased significantly with the infection of PDCoV, but not observed in UV irradiated PDCoV-infected cells, indicating that PDCoV infection activated both endogenous and exogenous apoptotic pathways in ST cells, and the induction of apoptosis depended on viral replication. To further investigate the endogenous apoptosis induced by PDCoV, cytochrome C and apoptosis-inducing factors in cytoplasm and mitochondria were detected. Compared with normal cells, the amount of cytochrome C released from mitochondria to cytoplasm increased significantly in PDCoV-infected cells, and the release increased with the prolongation of infection, while the apoptosis-inducing factor was always localized to mitochondria, suggesting that PDCoV induced apoptosis was initiated through caspase-dependent mitochondrial apoptosis pathway by promoting cytochrome C in the mitochondrial membrane gap into the cytosol. In conclusion, this study reveals the mechanism of PDCoV inducing apoptosis.