Figure 1. Alignment of the amino acid sequences including D187E, D222G, and Q223R mutants within the receptor binding site of H1N1pdm hemagglutinin.

E187, G222, and R223 variants obtained from three clinical specimens (#1, #2, and #3) from the first wave of the outbreak. Three clinical nasal swabs were each subjected to RNA extraction, RT-PCR, and TA cloning. More than one hundred clones per specimen were sequenced using conventional Sanger technology. Positions 187, 222, and 223 are shown in bold and are underlined.