Porcine epidemic diarrhea virus (PEDV) is the causative agent of porcine epidemic diarrhea, causing substantial economic losses to the swine industry worldwide. However, the development of PEDV vaccine is hampered by its low propagation titer in vitro, due to difficulty in adapting to the cells and complex culture conditions, even in the presence of trypsin. Furthermore, the frequent variation, recombination, and evolution of PEDV resulted in reemergence and vaccination failure. In this study, we established the Vero/TMPRSS2 and Vero/MSPL cell lines, constitutively expressing type II transmembrane serine protease TMPRSS2 and MSPL, in order to increase the stability and titer of PEDV culture and isolation in vitro. Our study revealed that the Vero/TMPRSS2, especially Vero/MSPL cell lines, can effectively facilitate the titer and multicycle replication of cell-adapted PEDV in the absence of exogenous trypsin, by cleaving and activating PEDV S protein. Furthermore, our results also highlighted that Vero/TMPRSS2 and Vero/MSPL cells can significantly enhance the isolation of PEDV from the clinical tissue samples as well as promote viral infection and replication by cell-cell fusion. The successful construction of the Vero/TMPRSS2 and Vero/MSPL cell lines provides a useful approach for the isolation and propagation of PEDV, simplification of virus culture, and large-scale production of industrial vaccine, and the cell lines are also an important system to research PEDV S protein cleaved by host protease.

中文翻译：

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表达TMPRSS2和MSPL的稳定Vero细胞系的建立：在没有外源胰蛋白酶的情况下传播猪流行性腹泻病毒的有用工具。

猪流行性腹泻病毒（PEDV）是猪流行性腹泻的病原体，给全世界的养猪业造成了巨大的经济损失。但是，由于即使在存在胰蛋白酶的情况下也难以适应细胞和复杂的培养条件，因此PEDV疫苗的体外繁殖滴度低阻碍了其发展。此外，PEDV的频繁变异，重组和进化导致重新出现和疫苗接种失败。在这项研究中，我们建立了Vero / TMPRSS2和Vero / MSPL细胞系，以组成型表达II型跨膜丝氨酸蛋白酶TMPRSS2和MSPL，以提高PEDV培养和体外分离的稳定性和效价。我们的研究表明，Vero / TMPRSS2，尤其是Vero / MSPL细胞系，通过裂解和激活PEDV S蛋白，可以有效地促进在没有外源胰蛋白酶的情况下细胞适应性PEDV的效价和多周期复制。此外，我们的结果还强调了Vero / TMPRSS2和Vero / MSPL细胞可以显着增强从临床组织样品中分离PEDV的能力，并通过细胞-细胞融合促进病毒感染和复制。Vero / TMPRSS2和Vero / MSPL细胞系的成功构建为PEDV的分离和繁殖，病毒培养的简化以及工业疫苗的大规模生产提供了有用的方法，并且细胞系也是重要的系统研究被宿主蛋白酶切割的PEDV S蛋白。我们的研究结果还强调，Vero / TMPRSS2和Vero / MSPL细胞可以显着增强临床组织样品中PEDV的分离，并通过细胞-细胞融合促进病毒感染和复制。Vero / TMPRSS2和Vero / MSPL细胞系的成功构建为PEDV的分离和繁殖，病毒培养的简化以及工业疫苗的大规模生产提供了有用的方法，并且细胞系也是重要的系统研究被宿主蛋白酶切割的PEDV S蛋白。我们的研究结果还强调，Vero / TMPRSS2和Vero / MSPL细胞可以显着增强临床组织样品中PEDV的分离，并通过细胞-细胞融合促进病毒感染和复制。Vero / TMPRSS2和Vero / MSPL细胞系的成功构建为PEDV的分离和繁殖，病毒培养的简化以及工业疫苗的大规模生产提供了有用的方法，并且细胞系也是重要的系统研究被宿主蛋白酶切割的PEDV S蛋白。