The polarity of zanamivir enables inhibition of the I223R mutant.

<p>In panel A, hydrogen bond contacts are presented (dotted lines), which are formed between zanamivir and active site residues in the I223R mutant (purple, PDB ID code 4B7N). The insert displays the interactions between the same residues in the I223R mutant ligand-free structure (blue, PDB ID code 4B7M). In panel B, active site residues and hydrogen bonds are displayed, which are formed in the wild type zanamivir structure complex (brown, PDB ID code 4B7Q). The insert displays the I223, S247 and E277 residues in the wild type ligand-free structure.