The researchers found that no genes in H7N9 were traceable to pigs, thus
excluding pigs as intermediate hosts for the deadly new strain of bird
flu, the Chinese Academy of Sciences' Key Laboratory of Pathogenic
Microbiology and Immunology said on Wednesday.
According to the
researchers, the genetic reassortment is likely to have occurred in east
China's Yangtze River Delta areas covering Shanghai, Zhejiang and
Jiangsu. They found that a virus carried by wild birds from the Republic
of Korea and other east Asian regions mingled with the avian influenza
virus carried by ducks and chickens in the Yangtze River Delta during
The lab's research shows the H7 and N9 gene segments
in H7N9 are similar to those in avian influenza samples collected from
wild birds from east Asia, while the other six genes are traceable to
chickens in China's Shanghai, Zhejiang and Jiangsu.