Pandemic Avian Influenza and Intra/Interhaemagglutinin Subtype Electrostatic Variation among Viruses Isolated from Avian, Mammalian, and Human Hosts

Figure 2

Electrostatic isocontours and fingerprints for haemagglutinin HA1 chains from H5 virus couples, representative for each group (as defined by ED analysis presented in Figure 1). Avian host-virus is missing for G6. Four, 90° stepwise rotation views are provided for each isocontour. Colour coding associated with avian (a), human (h), or other mammalian (m) hosts is the same as in heatmap figures. The three main subregions of the HA1 chain are depicted at the top-left corner. For specific virus numbering please refer to the complete dataset as presented in Supplementary Figure . Fingerprints are highlighted by green and yellow boxes. Group 1 (G1) exhibits a negative charge (red) at the RBD-VED intermediate region (green box). In addition, this region shows a positive charge (blue), extending towards the F’ region (yellow box). Fingerprint in G2 is shaped as a negatively charged circle with inner central spot at the RBD (green box). A similar signature is found in G3, where the negative circle extends towards the F’ region (green box). G3 viruses also show a positive charge at the top of RBD (yellow box, shared with G5), whereas this region is less positive or even contains negative charge in other groups. G5 also shows a peculiar, very negative region at the RBD (green box). All groups but G4 share two or three positive spots at the top-left side (90° view) of the RBD; this region is green boxed in G4 to highlight missing dots. G6 viruses show a negative region located at the RBD-VED interface with rhomboid shape and a central, neutral (white) spot peculiar to this group (green box). A large negative area at the RBD + VED is evident in G7, being homogeneously red at the VED (green box) and dispersed at the RBD (yellow box).