Fig. 4From: Diversity and distribution of type A influenza viruses: an updated panorama analysis based on protein sequencesPhylogenetic diversity and distribution of H4 subtypes of IAVs based on HA sequences. H4 subtype IAVs were classified into three primary lineages; H4.1 and H4.2 mainly corresponded to AIVs circulating in the North America; H4.3 corresponded to AIVs from both HemispheresBack to article page