Fig 3. Evolutionary relatedness of PA gene segments of H1N1 IAVs of avian, swine and human origins isolated from North America and Eurasia.
The taxa are colored based on their host and geography: red-North American avian isolates from the St. Jude repository, light blue-North American avian isolates, purple-Eurasian avian isolates, green- swine isolates from North America, grey- swine isolates from Eurasia (both Eurasian avian-like swine and Eurasian classical swine), dark blue-human isolates from North America; orange- human isolates from Eurasia, and pink- 2009 pandemic isolates. The nodes with spillover avian H1N1 IAVs are denoted with light blue arrows.