02.03.2014

Lancet Feb 26, 2014

The two novel influenza viruses that affect human beings, H7N9 and H10N8, have similar genetic lineage: the haemagglutinin (H) gene originated from ducks and the neuraminidase (N) gene from wild birds. Both H7N9 and H10N8 viruses possess internal gene cassettes recruited from poultry H9N2 virus. Long-term surveillance of poultry in China and east Asia shows that H9N2 virus is widely spread. Phylogenetics analyses suggest that different subtypes of avian influenza viruses cocirculated with H9N2 and have reassorted their internal genes. Although the contribution of H9N2 genes to infection in human beings needs to be determined, these genes probably enable H7N9 virus to survive and be transmitted within poultry, because dynamic reassortments of H7N9 with H9N2 genes have been observed, suggesting that H7N9 virus evolved in poultry to become a virus that infects human beings. Hence, reassortment between the prevalent poultry H9N2 viruses (providing genetic segments) and the influenza virus from wild birds could make the influenza evolve to adapt to domestic hosts. Poultry, especially in live markets, would have a pivotal role during the emergence of a novel influenza virus of avian origin. Slaughter of poultry carrying H9N2 - the incubators for wild-bird-origin influenza viruses - would be an effective strategy to prevent human beings from becoming infected with avian influenza. The researchers call for either a shutdown of live poultry markets or periodic thorough disinfections of these markets in China and any other regions with live poultry markets.