Fig. 1.

Phylogenetic relationships of HA genes of representative influenza A viruses isolated in Iran, Middle Eastern, Eurasian countries, and USA. The amino acid ranges of segments that were used for drawing phylogenic trees were the following: HA (1–560). Trees were generated by the neighbor-joining method with the MEGA 4 software. Numbers above branches indicate neighbor-joining bootstrap values. H9N2 viruses that were characterized in this study are indicated by red circles, Iranian pink rectangles, and Euroasian lineage green triangles. Virus name and abbreviations are shown in Table 1