We found previously unrecognized phylogenetic discordance between gene trees involving human and cat isolates (n = 25, denoted in red in Figures 1, S1-S3)-the main focus of our study-suggesting that they are reassortant viruses descending from group 2 and 3 lineages. In addition, the placement of two avian viruses isolates from Java (Ck/IDN/Semerang1631-62/07 and Ck/IDN/Magelang1631-57/07, shown in blue in Figures 1A  and S2C ) differed between HA and NA phylogenies, suggesting another reassortment event.