Fig. 27From: Diversity and distribution of type A influenza viruses: an updated panorama analysis based on protein sequencesPhylogenetic diversity and distribution of IAVs based on PB2 gene sequences. Based on the viral PB2 gene sequences, IAVs were classified into four primary lineages, PB2.1, PB2.2, PB2.3, and PB2.4 which mainly corresponded to AIVs, HuIVs, SIVs, and EIVsBack to article page