Figure 1
From: Subtype-specific structural constraints in the evolution of influenza A virus hemagglutinin genes
Predicted RNA structure in domain 794–839 of the HA segment of human H3N2 viruses.
The sequence of influenza virus A/Hong Kong/68 (H3N2) is shown, representing the first H3N2 viruses in humans introduced in 1968. The main covariation events and amino acid changes caused by non-synonymous substitutions during subsequent evolution are shown in red.
