Isopotential contours of the RBD subregions from H5N1 clades 0 to 9. See Figure 1 caption for color code and definitions. Isopotential contours are plotted at ±1kBT/e. Specific mutations discussed in the text are highlighted. Positively charged residues are written in blue and negatively charged ones in red. Panels: models refined using SCWRL (A), ModRefiner (B) or not refined (C).