H7N9 Carries Genes from Rare H9N2, H7N3, H4N9, H11N9 Bird Flu Viruses
Apr 29, 2013
A team of microbiologists led by Prof Chen Hualan of the Harbin Veterinary Research Institute investigated the origins of a new influenza A (H7N9) virus by testing samples collected from live poultry markets and poultry farms located in Shanghai and Anhui Province, China.
The H7N9 influenza virus was isolated from humans in China in March, 2013. A total of 109 laboratory-confirmed cases of human infection with the virus have been reported as of April 25, 2013.
According to recent studies of H7N9 collected from live poultry markets, these viruses are reassortants in which the six internal genes were derived from avian H9N2 viruses. However, the origins of their hemagglutinin (HA) and neuraminidase (NA) genes have been unclear.
The team collected 970 samples (drinking water, feces, contaminated soil, and cloacal and tracheal swabs) from live poultry markets and poultry farms located in China. 20 samples were positive for the presence of H7N9 influenza viruses. All of the positive samples originated from live poultry markets in Shanghai. Ten of them were isolated from chickens, three from pigeons, and seven were from environmental samples.
The scientists sequenced the complete genome of three H7N9 isolates – from a chicken, pigeon, and environmental sample. Genetic analysis of these isolates revealed high homology across all eight gene segments. Phylogenetic analysis of these novel H7N9 influenza virus isolates showed that that the six internal genes were derived from avian H9N2 viruses.