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.

Yongsen Ruan;Haijun Wen;Mei Hou;Ziwen He;Xuemei Lu;Yongbiao Xue;Xionglei He;Ya-Ping Zhang;Chung-I Wu

State Key Laboratory of Biocontrol,School of Life Sciences,Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Sun Yat-sen University,Guangzhou 510275,China;State Key Laboratory of Genetic Resources and Evolution,Kunming Institute of Zoology,Chinese Academy of Sciences,Kunming 650223,China;Beijing Institute of Genomics,Chinese Academy of Sciences,and China National Centre for Bioinformation,Beijing 100101,China;Department of Ecology and Evolution,University of Chicago,Chicago,IL 60637,USA

国家科学评论（英文版）

[1]Yongsen Ruan;Haijun Wen;Mei Hou;Ziwen He;Xuemei Lu;Yongbiao Xue;Xionglei He;Ya-Ping Zhang;Chung-I Wu-.The twin-beginnings of COVID-19 in Asia and Europe—one prevails quickly)[J].国家科学评论（英文版）,2022(04):46-54

beginnings,C241T,C3037T,C14408T,A23403G,Curiously,DG1111,DG0000,supplanted,replayed

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