Phylogenetic relationships of the polymerase acidic protein (PA) (A) and nucleocapsid protein (NP) (B) genes of influenza A (H5N1) viruses in Indonesia. All trees were generated by neighbor-joining in ClustalW (www.clustal.org). Numbers above or below branches indicate neighbor-joining bootstrap values. Analyses were based on nucleotides 1426–2172 (747 bp) and 46–913 (868 bp) of the PA and NP genes, respectively. Each tree was rooted to A/duck/Guangxi/50/2001. Colors indicate swine isolates (blue) and chicken isolates (red) most closely related to swine viruses. Scale bar indicates 0.01 nt substitutions per site. Ck, chicken; Dk, duck; Fl, feline; Gx, Guangxi; HK, Hong Kong; IDN, Indonesia; Qa, quail; ST, Shantou; Sw, swine.