[Complete genome phylogenetic analysis of five H9N2 avian influenza viruses isolated from poultry flocks in Qinghai lake region].

Five H9N2 avian influenza virus strains were isolated from the environmental samples in live poultry market in Qinghai Lake region from July to September, 2012. To evaluate the phylogenetic characteristics of these H9N2 isolates, the eight gene segments were amplified by RT-PCR and sequenced. The phylogenetic and molecular characteristics of the five strains were analyzed. The results showed that the HA genes of five strains shared 93. 2%-99. 1% nucleotide identities with each other, and the NA genes shared 94. 5%-99. 8% nucleotide identities. The HA cleavage site sequence of the A/environment/qinghai/ 017/2012 isolate was PSKSSRGLF, and the HA cleavage site sequences of the other four strains were all PSRSSRGLF. The HA receptor-binding site had the Q226L mutation. The M1 gene segment had the N30D and T215A mutations. The phylogenetic analysis showed that the five strains were similar to the virus A/chicken/Hunan/5260/2005 (H9N2) isolated in Hunan Province, China and were reassortant genotype viruses; the HA, NA, and NS genes belonged to the Y280-like lineage; the MP gene belonged to the G1-like lineage; the NP, PB1, PB2, and PA genes belonged to the F98-like lineage.