A latest study conducted by the research team led by Dr. Chen Hualan of Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences (HVRI-CAAS) revealed that the H7N9 influenza virus in humans had a similar genome sequence to that of H7N9 virus found in live poultry markets. This study for the first time identified the source of the novel H7N9 influenza viruses, providing an important basis for the control and prevention of H7N9 viruses in China. This research finding was published in June, 2013 on Chinese Science Bulletin (volume 58, 16:1857-1863)

The research results indicated that the six internal genes of the H7N9 virus were derived from the H9N2 virus, but origins of both its hemagglutinin (HA) gene and neuraminidase (NA) gene were not clear. Sequence analysis revealed that the H7N9 virus had partially acquired human-type receptor-binding specificity. Importantly, the H7N9 virus acquired critical mutations during their replication in human host, which may significantly contribute to its capacity to infect and kill humans.

http://link.springer.com/content/pdf/10.1007/s11434-013-5873-4.pdf