The NCBI influenza virus resource was used to download 11,981 full-length, non-redundant Influenza hemagglutinin protein sequences (August 2011). Homologs were aligned using MUSCLE and saved in MSF format. Dataset for reference: Roca AI, et al. ProfileGrids Solve the Large Alignment Visualization Problem: Influenza Hemagglutinin Example. F1000Research 2:2 (2013)