Fig. 1. The Omicron (B.1.1.529) variant is characterized by the cluster of mutations in the spike protein.
(A) Amino acid mutations in the spike protein are shown for the indicated SARS-CoV-2 strains. Mutation frequencies of each amino acid substitution in the spike protein were calculated using SARS-CoV-2 sequences reported in GISAID as 17th Dec 2021 (Alpha = 1,138,704; Beta = 40,135; Gamma = 117,200; Delta = 3,441,137, and Omicron = 5,469 sequences). The circle size and color represent the mutation frequency according to the scale shown at the right. (B) A structural model of the SARS-CoV-2 spike trimer with all three RBDs in the open state based on PDB: 7A89 is shown. In the RBD, the RBM is highlighted in dark blue, and Omicron mutations are highlighted in purple or red in or outside the RBM. (C) The relative proportions of variant cases during 2021 in South Africa, United Kingdom, North America, and Asia are shown.