Characterization of H9N2 influenza viruses isolated from Dongting Lake wetland in 2007.

In 2007, a total of eight H9N2 influenza viruses were isolated from the water and fowl feces in Dongting Lake wetland, China. The genomes of the eight viruses were sequenced, and all eight gene segments were subjected to phylogenetic analysis. The results showed that all the isolates belonged to the same genotype, in which the HA, NA and NS gene segments were Chicken/Beijing/94-like; the PB2, PB1, PA and NP gene segments were Chicken/Shanghai/F/98-like; and the M gene was Quail/Hong Kong/G1/97-like. Animal experiments showed low pathogenicity of the selected viruses for chickens, although some chickens died after inoculation. The viruses showed no overt clinical signs in mice, but they could replicate in murine lungs prior to adaptation.