FIG 2 Amino acid sequence conservation of four linear peptide example sequences from three human coronavirus proteins. Protein sequence alignments are shown for nucleocapsid (N), membrane (M), and ORF1ab polyprotein (helicase) across all five known human betacoronaviruses (SARS-CoV-2, SARS-CoV, HKU1, OC43, and MERS-CoV) and two known human alphacoronaviruses (229E and NL63). Each row in the three depicted sequence alignments corresponds to the protein sequence from the indicated coronavirus, with the starting coordinate of the viral protein sequence shown at left and position coordinates of the overall alignment displayed above. Blue shading indicates the extent of sequence identity, with the darkest blue shading indicating a 100% match for that amino acid across all sequences. The four red-highlighted sequences correspond to highly conserved peptides ≥8 amino acids in length (PRWYFYYLGTGP, WSFNPETN, QPPGTGKSH, and VYTACSHAAVDALCEKA, see Table S2).