The comparison of the total and the key residues of 100F4, 65C6, AVFluIgG01, AVFluIgG03, FLA5.10 and FLD21.140 epitopes. (A) The amino acid sequence alignment of the total and the key residues of 100F4, 65C6, AVFluIgG01, AVFluIgG03, FLA5.10 and FLD21.140 epitopes among selected HPAI H5 strains compared to parental HPAI H5N1 virus. The key residues of these epitopes were defined as a single amino acid mutation that results in a 3-fold or more decrease in neutralization or binding activity of a given antibody. Key residues of each epitope are highlighted in red bold font. (B) The summary of the total and the key residues, as well as the mutations in the total and the key residues of 100F4, 65C6, AVFluIgG01, AVFluIgG03, FLA5.10 and FLD21.140 epitopes among selected HPAI H5 strains. n.d. stands for not determined. Co-cry: co-crystallization. GFPDL: Gene-Fragmented Phage Display Libraries. RPL: Random Peptide phage display Library.