Serial cell culture passaging in vitro led to complete attenuation and changes in the characteristic features of a virulent porcine deltacoronavirus strain

文献类型： 外文期刊

第一作者： Zhang, Liping

作者： Zhang, Liping;Yu, Ruiming;Wang, Lianshun;Zhang, Zhongwang;Lu, Yanzhen;Zhou, Peng;Wang, Yonglu;Guo, Huichen;Pan, Li;Liu, Xinsheng;Zhang, Liping;Yu, Ruiming;Wang, Lianshun;Zhang, Zhongwang;Lu, Yanzhen;Pan, Li;Liu, Xinsheng;Zhang, Liping;Yu, Ruiming;Wang, Lianshun;Zhang, Zhongwang;Lu, Yanzhen;Zhou, Peng;Wang, Yonglu;Guo, Huichen;Pan, Li;Liu, Xinsheng

作者机构：

关键词： porcine deltacoronavirus; passage; attenuation; pigs; pathogenicity

期刊名称：JOURNAL OF VIROLOGY （ 影响因子：4.0； 五年影响因子：4.0 ）

ISSN： 0022-538X

年卷期： 2024 年 98 卷 8 期

页码：

收录情况： SCI

摘要： Porcine deltacoronavirus (PDCoV) is an important enteric coronavirus that has caused enormous economic losses in the pig industry worldwide. However, no commercial vaccine is currently available. Therefore, developing a safe and efficacious live-attenuated vaccine candidate is urgently needed. In this study, the PDCoV strain CH/XJYN/2016 was continuously passaged in LLC-PK cells until passage 240, and the virus growth kinetics in cell culture, pathogenicity in neonatal piglets, transcriptome differences after LLC-PK infection, changes in the functional characteristics of the spike (S) protein in the high- and low-passage strains, genetic variation of the virus genome, resistance to pepsin and acid, and protective effects of this strain when used as a live-attenuated vaccine were examined. The results of animal experiments demonstrated that the virulent PDCoV strain CH/XJYN/2016 was completely attenuated and not pathogenic in piglets following serial cell passage. Genome sequence analysis showed that amino acid mutations in nonstructural proteins were mainly concentrated in Nsp3, structural protein mutations were mainly concentrated in the S protein, and the N, M, and E genes were conserved. Transcriptome comparison revealed that compared with negative control cells, P10-infected LLC-PK cells had the most differentially expressed genes (DEGs), while P0 and P240 had the least number of DEGs. Analysis of trypsin dependence and related structural differences revealed that the P10 S protein interacted more strongly with trypsin and that the P120 S protein interacted more strongly with the APN receptor. Moreover, the infectivity of P240 was not affected by pepsin but was significantly decreased after exposure to low pH. Furthermore, the P240-based live-attenuated vaccine provided complete protection to piglets against the challenge of virulent PDCoV. In conclusion, we showed that a PDCoV strain was completely attenuated through serial passaging in vitro. These results provide insights into the potential molecular mechanisms of PDCoV attenuation and the development of a promising live-attenuated PDCoV vaccine.

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