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Title: Changes in adaptation of H5N2 highly pathogenic avian influenza H5 clade 2.3.4.4 viruses in chickens and mallards

Author
item DeJesus, Eric
item COSTA-HURTADO, MAR - Orise Fellow
item Smith, Diane
item LEE, DONG-HUN - Orise Fellow
item Spackman, Erica
item Kapczynski, Darrell
item TORCHETTI, MIA - Animal And Plant Health Inspection Service (APHIS)
item KILLIAN, MARY - Animal And Plant Health Inspection Service (APHIS)
item Suarez, David
item Swayne, David
item Pantin Jackwood, Mary

Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2016
Publication Date: 8/31/2016
Publication URL: https://handle.nal.usda.gov/10113/63161
Citation: Dejesus, E.G., Costa-Hurtado, M., Smith, D.M., Lee, D., Spackman, E., Kapczynski, D.R., Torchetti, M.K., Killian, M.L., Suarez, D.L., Swayne, D.E., Pantin Jackwood, M.J. 2016. Changes in adaptation of H5N2 highly pathogenic avian influenza H5 clade 2.3.4.4 viruses in chickens and mallards. Virology. 499:52-64. doi:10.1016/j.virol.2016.08.036.

Interpretive Summary: H5N2 highly pathogenic avian influenza (HPAI) viruses caused a severe poultry outbreak in the United States (U.S.) in which over 7.5 million turkeys and 42.1 million chickens died or were depopulated in efforts to control the disease. The epidemiology of the H5 HPAI virus detections suggested that the initial H5N2 viruses detected in the U.S. were highly adapted to waterfowl and not yet well adapted to domestic poultry. However, multi-generational passage in chickens or turkeys could have generated viruses more adapted to poultry. In order to examine changes in adaptation of the H5N2 viruses, the infectivity, transmission and pathogenesis of poultry H5N2 viruses was investigated in chickens and mallards in comparison to the wild duck 2014 index H5N2 virus. The four poultry isolates examined were more infectious than the index virus but still transmitted poorly to direct contacts. In mallards, two H5N2 poultry isolates had similar high infectivity and transmissibility but interestingly, one of them caused mortality. In conclusion, increased adaptation to chickens was observed with the newer poultry H5N2 viruses; however these viruses retained high adaptation to mallards but pathogenicity was affected in differing ways.

Technical Abstract: H5N2 highly pathogenic avian influenza (HPAI) viruses caused a severe poultry outbreak in the United States (U.S.) during 2015. In order to examine changes in adaptation of this viral lineage, the infectivity, transmission and pathogenesis of poultry H5N2 viruses was investigated in chickens and mallards in comparison to the wild duck 2014 U.S. index H5N2 virus. The four poultry isolates examined had a lower bird infectious dose50 than the index virus but still transmitted poorly to direct contacts. In mallards, two H5N2 poultry isolates had similar high infectivity and transmissibility as the index H5N2 virus, the H5N8 U.S. index virus, and a 2005 H5N1 clade 2.2 virus. Interestingly, mortality occurred with the H5N1 clade 2.2 virus and one of two poultry H5N2 isolates. Increased adaptation to chickens was observed with the newer poultry H5N2 viruses; however these viruses retained high adaptation to mallards but pathogenicity was affected in differing ways.