Title: Pathogenesis and transmission of H7N9 influenza virus in poultry Authors
|Torchetti, Mia -|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 25, 2013
Publication Date: July 7, 2013
Citation: Pantin Jackwood, M.J., Miller, P.J., Spackman, E., Swayne, D.E., Torchetti, M., Susta, L., Suarez, D.L. 2013. Pathogenesis and transmission of H7N9 influenza virus in poultry [abstract]. Centers for Excellence in Influenza Research and Surveillance meeting, July 7-10, 2013, Memphis, Tennessee. p. 36. Technical Abstract: The recent outbreaks of H7N9 influenza in China has resulted in many human cases with a high fatality rate. Poultry have been suspected as the source of infection based on sequence analysis and virus isolations from live bird markets, but it’s not clear which species of birds are most likely to be infected and shedding sufficient levels of virus to infect humans. Intranasal inoculation of chickens, turkeys, Japanese quail, pigeons, Pekin ducks, Mallard ducks, Muscovy ducks, and Embden geese with 106 EID50 of the A/Anhui/1/2013 virus resulted in infection but no clinical signs. Virus shedding in quail, chickens, and Muscovy ducks was much higher and prolonged than in the rest of the species. Quail effectively transmitted the virus to direct contacts but pigeons and Pekin ducks did not. In all species, virus was detected at much higher titers from oropharyngeal swabs than cloacal swabs. The HA gene from samples collected from infected chickens and quail were sequenced to examine for changes in the virus after passage in these species. Three amino acid differences were observed when compared to A/Anhui/1/2013: N123D, N149D, and L217Q. Different combinations were present indicating most likely that the inoculum had virus subpopulations that were selected after passage in birds. In conclusion, these experimental studies corroborate that poultry species are an important reservoir of the H7N9 virus. The high levels of viral replication in the upper respiratory tract is characteristic of poultry-adapted influenza viruses, and consequentially testing of bird species should preferentially be conducted with OP swabs for best sensitivity.