Comparison of the amino acid sequences of different subtypes of influenza A virus HAs.

<p>Amino acids at positions from 145 to 204 are shown. Boxed residues indicate the positions 156 (blue), 158 (green), and 193 (red). Asterisks indicate conserved amino acid residues among HA subtypes examined. Amino acid sequences for HAs, except Adachi (H2) and W213 (H9), were downloaded from the Influenza Virus Resource at the National Center for Biotechnology Information (NCBI) (<a href="http://www.ncbi.nlm.nih.gov/genomes/FLU/FLU.html" target="_blank">http://www.ncbi.nlm.nih.gov/genomes/FLU/FLU.html</a>) <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1000350#ppat.1000350-Chang1" target="_blank">[48]</a>. The NCBI accession numbers are CAA24272 (PR8), AAA43209 (WSN), AB432938 (Adachi), CAA24269 (Aichi), AAB63708 (Memphis), AAT7327 (VN1194), BAE48688 (Hok67), AB432937 (W213), and BAF46906 (Maryland).