Ruan Yongsen, Wen Haijun, Hou Mei, He Ziwen, Lu Xuemei, Xue Yongbiao, He Xionglei, Zhang Ya-Ping, Wu Chung-I
State Key Laboratory of Biocontrol, School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou510275, China.
State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming650223, China.
Natl Sci Rev. 2021 Dec 11;9(4):nwab223. doi: 10.1093/nsr/nwab223. eCollection 2022 Apr.
In the spread of SARS-CoV-2, there have been multiple waves of replacement between strains, each of which having a distinct set of mutations. The first wave is a group of four mutations (C241T, C3037T, C14408T and A23403G [this being the amino acid change D614G]; all designated 0 to 1 below). This DG (D614G) group, fixed at the start of the pandemic, is the foundation of all subsequent waves of strains. Curiously, the DG group is absent in early Asian samples but present (and likely common) in Europe from the beginning. European data show that the high fitness of DG1111 requires the synergistic effect of all four mutations. However, the European strains would have had no time to evolve the four DG mutations (0 to 1), had they come directly from the early Asian DG0000 strain. Very likely, the European DG1111 strain had acquired the highly adaptive DG mutations in pre-pandemic Europe and had been spreading in parallel with the Asian strains. Two recent reports further support this twin-beginning interpretation. There was a period of two-way spread between Asia and Europe but, by May 2020, the European strains had supplanted the Asian strains globally. This large-scale replacement of one set of mutations for another has since been replayed many times as COVID-19 progresses.
在严重急性呼吸综合征冠状病毒2（SARS-CoV-2）的传播过程中，不同毒株之间出现了多轮替代，每一轮都有一组独特的突变。第一轮是一组四个突变（C241T、C3037T、C14408T和A23403G [此为氨基酸变化D614G]；以下均标记为0至1）。这个DG（D614G）组在疫情开始时就已固定下来，是所有后续毒株浪潮的基础。奇怪的是，早期亚洲样本中没有DG组，但从一开始在欧洲就存在（且可能很常见）。欧洲的数据表明，DG1111的高适应性需要这四个突变的协同作用。然而，如果欧洲毒株直接来自早期亚洲的DG0000毒株，它们就没有时间进化出这四个DG突变（0至1）。很可能，欧洲的DG1111毒株在疫情前的欧洲就已获得了具有高度适应性的DG突变，并与亚洲毒株并行传播。最近的两份报告进一步支持了这种双起源的解释。亚洲和欧洲之间曾有过一段双向传播的时期，但到2020年5月，欧洲毒株已在全球范围内取代了亚洲毒株。自那以后，随着新冠疫情的发展，这种一组突变大规模替代另一组突变的情况已经多次重演。
