Figure 7.

Evolutionary relationships among H1 hemagglutinins of influenza A viruses from water birds (black branches) and the avian-like swine influenza clade (green branches; pink branches denote other swine strains that do not form part of the ‘avian-like’ swine influenza clade). A dark red marker indicates a phenylalanine at HA2 position 113, a yellow marker indicates a leucine and a bright green marker indicates an isoleucine. Serine at HA2 position 67 is indicated by a cross (blue if associated with serine at position 113, dark red if associated with a phenylalanine at position 113).