Fig. 1From: Diversity and distribution of type A influenza viruses: an updated panorama analysis based on protein sequencesPhylogenetic diversity and distribution of H1 subtypes of IAVs based on HA sequences. H1 subtype IAVs were classified into two primary lineages, H1.1 and H1.2. H1.1 mainly corresponded to H1 subtype AIVs and some SIVs which originated from the AIVs. H1.2 corresponded to classical H1 subtype HuIVs and SIVsBack to article page