FIG 1.

(A) Multiple sequence alignment of H9 HA. A total of 2,801 sequences obtained from NCBI Influenza Database (http://www.ncbi.nlm.nih.gov/genomes/FLU/FLU.html) were aligned by the MUSCLE alignment program. The HA cleavage site from P6 to P1 and the fusion peptide are shown. H9HA consensus sequence is indicated in boldface; underneath it are representative strains where sequence differences from the consensus H9 HA are indicated by the single-letter amino acid code. Representative strains and their accession numbers are as follows: A/duck/Hong Kong/W213/1997 (BAG72217), A/chicken/Hong Kong/G9/1997 (AAF00701), A/turkey/Wisconsin/1/1966 (BAA14335), A/turkey/Israel/810/2001 (ABS50802), A/ostrich/Eshkol/1436/2003(AAW29080), A/quail/Shantou/2061/2000 (ABM46232), A/chicken/Israel/786/2001 (ABS50800), and A/turkey/Israel/747/2005 (ABS50799). Pitou furin prediction scores of the representative strains, where positive values indicate favorable cleavage by furin with the value proportional to the predicted efficiency of cleavage of a given site, are listed. (B) Summary of strains harbors the same mutation as Israel810. This information was current during the preparation of the manuscript (August 2013).