Fig. 33From: Diversity and distribution of type A influenza viruses: an updated panorama analysis based on protein sequencesPhylogenetic tree of the viral HA gene representative sequences of H1 subtype. H1 subtype IAVs were classified into two primary lineages, H1.1 and H1.2, and each of them were further classified into four secondary lineages. Bootstrap values were given at relevant nodesBack to article page