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United States Department of Agriculture

Agricultural Research Service

Research Project: Intervention Strategies to Control and Prevent Disease Outbreaks Caused by Avian Influenza and Other Emerging Poultry Pathogens

Location: Exotic & Emerging Avian Viral Diseases Research

Title: Pathogenicity and transmission of H5 and H7 highly pathogenic avian influenza viruses in mallards

Author
item Pantin-jackwood, Mary
item Costa-hurtado, Mar
item Shepherd, Eric
item Dejesus, Eric
item Smith, Diane
item Spackman, Erica
item Kapczynski, Darrell
item Suarez, David
item Stallknecht, David
item Swayne, David

Submitted to: Journal of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2016
Publication Date: 8/24/2016
Publication URL: http://handle.nal.usda.gov/10113/5678141
Citation: Pantin Jackwood, M.J., Costa-Hurtado, M., Shepherd, E.M., Dejesus, E.G., Smith, D.M., Spackman, E., Kapczynski, D.R., Suarez, D.L., Stallknecht, D., Swayne, D.E. 2016. Pathogenicity and transmission of H5 and H7 highly pathogenic avian influenza viruses in mallards. Journal of Virology. 90(21):9967-9982.

Interpretive Summary: Highly pathogenic avian influenza (HPAI) viruses remain a threat to poultry worldwide. With the continuous occurrence of HPAI outbreaks in poultry it’s important to address the role of wild birds in the transmission and spread of HPAI. Wild aquatic birds have been associated with the spread of H5 subtype HPAI viruses of the A/goose/Guangdong/1/96 (Gs/GD) lineage around the world, but not with the spread of other HPAI viruses. In order to understand why Gs/GD H5 HPAI viruses infect and transmit better in ducks than other HPAI viruses we conducted a study in which we inoculated mallards with one of fourteen strains of HPAI viruses subtypes H5 or H7, including the United States Gs/GD H5 lineage viruses that caused the outbreaks in poultry in 2015. Pathogenesis (clinical signs, lesions), presence of the viruses in tissues, duration and titer of virus shedding, transmission to contact birds, and seroconversion to all viruses was evaluated. All virus-inoculated ducks and contact exposed ducks became infected and shed moderate to high titers of the viruses, with the exception of ducks inoculated with Ck/Pennsylvania/83 and Ck/Queretaro/95 H5N2 HPAI viruses. Clinical signs were only observed in ducks infected with a Gs/GD lineage H5N1 virus, which all died, and the H5N8 and H5N2 2014 viruses, which had decreased weight gain and fever. These three viruses were also shed in higher titers by the ducks, which could facilitate virus transmission and spread.

Technical Abstract: Wild aquatic birds have been associated with the intercontinental spread of H5 subtype highly pathogenic avian influenza (HPAI) viruses of the A/goose/Guangdong/1/96 (Gs/GD) lineage during 2005, 2010 and 2014, but dispersion by wild waterfowl has not been implicated with spread of other HPAI viruses. To better understand why Gs/GD H5 HPAI viruses infect and transmit more efficiently in waterfowl than other HPAI viruses, groups of mallards were challenged with one of fourteen different H5 and H7 HPAI viruses, including a Gs/GD lineage H5N1 (clade 2.2) virus from Mongolia, part of the 2005 dispersion, and the H5N8 and H5N2 index HPAI viruses (clade 2.3.4.4) from the United States, part of the 2014 dispersion. All virus-inoculated ducks and contact exposed ducks became infected and shed moderate to high titers of the viruses, with the exception that mallards were resistant to Ck/Pennsylvania/83 and Ck/Queretaro/95 H5N2 HPAI viruses. Clinical signs were only observed in ducks challenged with the H5N1 2005 virus, which all died, and the H5N8 and H5N2 2014 viruses, which had decreased weight gain and fever. These three viruses were also shed in higher titers by the ducks, which could facilitate virus transmission and spread. This study highlights the possible role of wild waterfowl in the spread of HPAI viruses.

Last Modified: 10/16/2017
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