Location of identified amino acid mutations in A/Vietnam/1203/2004 H5N1 PA. The N-terminal region of A/Vietnam/1203/2004 H5N1 PA protein (accession no. AY818132) is shown in two different views using the same coloring code. PA is indicated in gray. Locations of amino acids L16, N33, K34, E43, F76, P107, L132, H146, I147, E153, R170, L187, and F191 (red), E101/R125 (blue), and or D111/E196 (green) are shown on the background of the PA. The crystal structure figure was adapted from PDB 4E5E using PyMOL.