Submitted to: International Symposium on Avian Influenza
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2015
Publication Date: 4/12/2015
Citation: Rodriguez, M., Suarez, D.L. 2015. The poor transmission of the Chinese A/Anhui/1/2013 H7N9 virus in chickens is directly related to the hemagglutinin gene [abstract]. 9th International Symposium on Avian Influenza. p. 46.
Technical Abstract: The H7N9 Chinese low pathogenic avian influenza viruses are a zoonotic threat and have infected hundreds of people over the last two years. The virus has been found in poultry, particularly in live bird markets, and poultry exposure in the markets is suspected of being the main source of infection for humans. The H7N9 viruses have an internal gene cassette from poultry adapted H9N2 viruses that have been endemic in China for many years, and it was predicted that these viruses would be adapted to chickens. However, the H7N9 chicken infectious dose 50 is high and the virus transmits poorly to naïve direct contact chickens, suggesting that the virus is not well adapted to chickens. To determine the genes responsible for infection and direct contact transmission, a reverse genetics system was established using the A/Anhui/1/2013 (Anhui/13) virus as a backbone, and different reassortant viruses were created from viruses circulating in China. The parent RG Anhui/13 infected most chickens with a moderate level of oral viral shedding, but the virus transmitted poorly to contact controls. The substitution of several internal genes gave a similar replication and transmission pattern. However, when the HA and NA genes were substituted with H9 and N2 genes, virus shedding increased and readily transmitted virus to contact controls. Alternative viruses with the same H9 gene and a N7 gene on the Anhui/13 backbone also replicated and transmitted well. This data supports the hemagglutinin gene as being the principal determinant of H7N9 replication and transmission in chickens.