Figure 5

Distribution of d _N / d _S  values across avian influenza H7 HA1 sites, on different NA subtype backgrounds. The d _N value for each site was divided by the average d _S across all sites for that subtype to obtain a d _N /d _S value for each site on each background NA subtype. Sites with d _N /d _S > 1, i.e. under putative positive selection, are highlighted in red. Sites under putative positive selection were distributed across the HA1 for all background NA subtypes. Although there is some variation between NA backgrounds in terms of the sites under putative positive selection, there is also some commonality between the subtypes (see Additional file 1: Table S1). A coloured key is provided, which indicates the HA1 domain: fusion (pink), vestigial esterase (green) or receptor binding (blue). The signal peptide region is indicated in yellow.