H3N2 Influenza Virus Transmission from Swine to Turkeys, United States
Figure. Phylogenetic tree representing the HA nucleotide sequences of two H3N2 influenza viruses isolated from turkeys on geographically distant farms in the United States and of selected swine influenza virus strains. Nucleotide sequences were aligned by using the Clustal_X (19) program, and phylograms were generated by the neighbor-joining method using the NJplot program (20). The scale is proportional to the numbers of substitutions per nucleotide.