FIG 7.

Sequence logos of the 2nd SIA-binding site of avian and human N1 proteins. Sequence logos were generated for the three loops that constitute the 2nd SIA-binding site using the WebLogo website (http://weblogo.berkeley.edu/) (40) using all sequences available of avian N1 viruses, human N1 viruses prior to 2009 (seasonal human N1), and human H1N1pdm09 viruses from 2009 to 2014 (pandemic human N1) via the Influenza Research Database (https://www.fludb.org/). Asterisks indicate SIA contact residues according to the N9 crystal structure (7).