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Title: The multigenic nature of the differences in pathogenicity of H5N1 highly pathogenic avian influenza viruses in domestic ducks

Author
item Pantin Jackwood, Mary
item WASILENKO, JAMIE - Food Safety Inspection Service (FSIS)
item Spackman, Erica
item Smith, Diane
item COSTA HURTADO, MAR - Orise Fellow
item SHEPHERD, ERIC - Former ARS Employee
item DEJESUS, ERIC - US Department Of Agriculture (USDA)
item LEE, DONG-HUN - Orise Fellow
item Swayne, David
item Suarez, David

Submitted to: American Association of Avian Pathologists
Publication Type: Abstract Only
Publication Acceptance Date: 1/10/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The Eurasian H5N1 highly pathogenic avian influenza (HPAI) viruses have evolved into many genetic lineages. The divergent strains that have arisen express distinct pathobiological features and increased virulence for many bird species including domestic waterfowl. The pathogenicity of H5N1 HPAI viruses in domestic ducks varies depending on the virus strain; however, the viral factors contributing to these differences in pathogenicity are not well understood. We determined the pathogenicity of more than 30 H5N1 HPAI viruses in Pekin ducks and conducted full genome sequence comparisons of the viruses, but failed to find common virulence markers. In order to determine which viral genes and specific changes contribute to the virulence of H5N1 HPAI viruses in ducks, we also used reverse genetics to generate single-gene reassortant viruses with genes from viruses differing in virulence. Exchange of the hemagglutinin (HA) or neuraminidase (NA) viral genes of A/duck/Vietnam/201/05 (virulent virus) (HA clade 2.4) in the A/chicken/Indonesia/7/03 (non-virulent virus) (HA clade 1) background, resulted in increased mortality in ducks. However, different results were obtained with reassortant viruses generated from two H5N1 HPAI viruses from Egypt (both HA clade 2.3.1), also exhibiting different virulence in ducks, where more than one gene was involved in increased virulence. In conclusion, the factors influencing virulence of H5N1 HPAI viruses in ducks appear to be multigenic and cannot be attributed to one specific gene or genetic change.