Fig. 1.

Mutations characterizing the S-gene of the BA.1 lineage viruses. Amino acid changes resulting from nonsynonymous substitutions relative to the Wuhan-Hu-1 sequence are indicated in: Blue, those attributable to nucleotide substitutions at codon sites that are either negatively selected or are evolving under no detectable selection in non-Omicron sequences and cluster within three regions labeled here as cluster regions 1, 2, and 3; Red, those attributable to nucleotide substitutions at codon sites that are detectably evolving under positive selection in non-Omicron sequences; and Black, those attributable to insertion and deletion mutations. NTD, N-terminal domain; RBD, receptor-binding domain; SD1/SD2, subdomain 1 and 2; FP, fusion peptide; HR1, heptad repeat 1; CH, central helix; CD, connector domain; HR2, heptad repeat 2; CT, cytoplasmic tail.