Figure. Phylogenetic tree of H5 hemagglutinin genes of influenza A viruses. The 3 H5 western Siberian 2005 viruses isolated in this study are shaded. Phylogenetic analysis was performed by the neighbor-joining method with the Molecular Evolutionary Genetic Analysis 2 program (Center for Evolutionary Functional Genomics, Tempe, AZ, USA). Scale bar indicates relative value of distance in matrix normalized units. Numbers indicate tree divarication.