Fig 7.

Sequence alignment of the PB2 cap-binding domain from human and swine influenza A viruses. The secondary structure of A/WSN/1933 is shown over the sequence alignment of strains sensitive to BPR3P0128 (Table 1). Residues His357 and Phe404 of influenza A virus indicated by underlining are principal residues in contact with the cap analogue m⁷GTP. Phe404 is conserved in influenza A and B viruses, whereas His357 is exclusive to influenza A virus and is replaced by a tryptophan in influenza B virus (22). The full-length PB2 sequences of the influenza B virus tested (Table 1) were not available in the public domain. Four representative sequences from 2005 and 2007 from NCBI are shown here.