The phylogenetic tree and the protein structure of bird type II IFN receptors. (a) The phylogenetic tree of the type II IFN receptors. It was built by MEGA5 program with 1000 bootstrap replicates and based on the neighbor-joining method. For IFNGR1, dark orange, green, pink in the picture represent birds, reptiles and amphibians, mammals, respectively. For IFNGR2, pink, light orange, light blue in the picture represent mammals, reptiles and amphibians, birds, respectively; and (b) The structure of bird type II IFN receptors. IFNGR1 reference sequences: Gallus gallus [GenBank: NP001123859.1], Melopsittacus undulatus [GenBank: XP005154885.1], Homo sapiens [GenBank: AAH05333.1], Rattus norvegicus [GenBank :EDL93784.1], Pelodiscus sinensis [GenBank: XP006112786.1]. IFNGR2 reference sequences: Gallus gallus [GenBank: AAV67776.1], Taeniopygia guttata [GenBank: XP002189244.2], Zonotrichia albicollis [GenBank: XP005497041.1], Mus musculus [GenBank: AAC52938.1], Anolis carolinensis [GenBank: AGL76447.1].