Graduate Institute of Veterinary Pathobiology, College of Veterinary Medicine, National Chung Hsing University, Taichung 40227, Taiwan.
Department of Microbiology and Immunology, School of Medicine, Chung-Shan Medical University and Clinical Laboratory, Chung-Shan Medical University Hospital, Taichung 40201, Taiwan.
Cells. 2020 Oct 19;9(10):2322. doi: 10.3390/cells9102322.
Coronaviruses are able to establish persistence. However, how coronaviruses react to persistence and whether the selected viruses have altered their characteristics remain unclear. In this study, we found that the persistent infection of bovine coronavirus (BCoV), which is in the same genus as SARS-COV-2, led to alterations of genome structure, attenuation of gene expression, and the synthesis of subgenomic mRNA (sgmRNA) with a previously unidentified pattern. Subsequent analyses revealed that the altered genome structures were associated with the attenuation of gene expression. In addition, the genome structure at the 5' terminus and the cellular environment during the persistence were responsible for the sgmRNA synthesis, solving the previously unanswered question regarding the selection of transcription regulatory sequence for synthesis of BCoV sgmRNA 12.7. Although the BCoV variants (BCoV-p95) selected under the persistence replicated efficiently in cells without persistent infection, its pathogenicity was still lower than that of wild-type (wt) BCoV. Furthermore, in comparison with wt BCoV, the variant BCoV-p95 was not able to efficiently adapt to the challenges of alternative environments, suggesting wt BCoV is genetically robust. We anticipate that the findings derived from this fundamental research can contribute to the disease control and treatments against coronavirus infection including SARS-CoV-2.
冠状病毒能够建立持续性感染。然而，冠状病毒如何对持续性感染做出反应，以及所选病毒是否改变了它们的特征，目前尚不清楚。在这项研究中，我们发现与 SARS-COV-2 同属一个属的牛冠状病毒（BCoV）的持续性感染导致基因组结构改变、基因表达减弱以及亚基因组 mRNA（sgmRNA）的合成出现以前未识别的模式。随后的分析表明，改变的基因组结构与基因表达减弱有关。此外，持续性感染过程中 5' 末端的基因组结构和细胞环境负责合成 sgmRNA，解决了先前关于选择转录调控序列来合成 BCoV sgmRNA 12.7 的未解决的问题。尽管在持续性感染下选择的 BCoV 变异株（BCoV-p95）在没有持续性感染的细胞中高效复制，但它的致病性仍然低于野生型（wt）BCoV。此外，与 wt BCoV 相比，变异株 BCoV-p95 无法有效地适应替代环境的挑战，这表明 wt BCoV 在遗传上具有更强的适应性。我们预计，这项基础研究的结果可以为包括 SARS-CoV-2 在内的冠状病毒感染的疾病控制和治疗做出贡献。
