Division of Virology, Institute of Medical Science, University of Tokyo, Tokyo, Japan; The Research Center for Global Viral Diseases, National Center for Global Health and Medicine Research Institute, Tokyo, Japan.
Division of Virology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
EBioMedicine. 2023 May;91:104561. doi: 10.1016/j.ebiom.2023.104561. Epub 2023 Apr 10.
The SARS-CoV-2 delta (B.1.617.2 lineage) variant was first identified at the end of 2020 and possessed two unique amino acid substitutions in its spike protein: S-P681R, at the S1/S2 cleavage site, and S-D950N, in the HR1 of the S2 subunit. However, the roles of these substitutions in virus phenotypes have not been fully characterized.
We used reverse genetics to generate Wuhan-D614G viruses with these substitutions and delta viruses lacking these substitutions and explored how these changes affected their viral characteristics in vitro and in vivo.
S-P681R enhanced spike cleavage and membrane fusion, whereas S-D950N slightly promoted membrane fusion. Although S-681R reduced the virus replicative ability especially in VeroE6 cells, neither substitution affected virus replication in Calu-3 cells and hamsters. The pathogenicity of all recombinant viruses tested in hamsters was slightly but not significantly affected.
Our observations suggest that the S-P681R and S-D950N substitutions alone do not increase virus pathogenicity, despite of their enhancement of spike cleavage or fusogenicity.
A full list of funding bodies that contributed to this study can be found under Acknowledgments.
SARS-CoV-2 德尔塔（B.1.617.2 谱系）变异株于 2020 年底首次被发现，其刺突蛋白上有两个独特的氨基酸取代：S1/S2 裂解位点的 S-P681R 和 S2 亚基 HR1 中的 S-D950N。然而，这些取代在病毒表型中的作用尚未完全阐明。
我们使用反向遗传学方法生成了具有这些取代的武汉-D614G 病毒和缺乏这些取代的德尔塔病毒，并探讨了这些变化如何影响它们在体外和体内的病毒特征。
S-P681R 增强了刺突蛋白的切割和膜融合，而 S-D950N 则略微促进了膜融合。尽管 S-681R 降低了病毒的复制能力，特别是在 VeroE6 细胞中，但这两种取代都没有影响病毒在 Calu-3 细胞和仓鼠中的复制。在仓鼠中测试的所有重组病毒的致病性都略有但无显著影响。
我们的观察结果表明，尽管 S-P681R 和 S-D950N 取代增强了刺突蛋白的切割或融合性，但它们单独作用并不会增加病毒的致病性。
可在致谢中找到为本研究做出贡献的全部资助机构的列表。
