Haemagglutinin cleavage site graphic.

I've added a new graphic to the H7N9 page that compares the important cleavage site in the immature HA protein among influenza A viruses, including H7N9. 

This shows that H7N9 is more similar to seasonal influenza viruses in this area-low-pathogenic viruses rather than high pathogenic viruses. 

The latter have a multiple basic amino acids at the cleavage site making them a target for proteases located throughout the body rather than just in the human respiratory system and bird gut.