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Title: Variability in pathobiology of South Korean H5N1 high-pathogenicity avian influenza virus infection for 5 species of migratory waterfowl

Author
item KWON, YONGKUK - Foreign Agricultural Service (FAS, USDA)
item Thomas, Colleen
item Swayne, David

Submitted to: Veterinary Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2009
Publication Date: 5/1/2010
Citation: Kwon, Y., Thomas, C., Swayne, D.E. 2010. Variability in pathobiology of South Korean H5N1 high-pathogenicity avian influenza virus infection for 5 species of migratory waterfowl. Veterinary Pathology. 47(3):495-506.

Interpretive Summary: The ability of H5N1 high pathogenicity avian influenza (HPAI) viruses to cause disease in wild waterfowl is poorly understood. This study examined the ability of a Korean strain of H5N1 HPAI virus to cause disease and death in five species of waterfowl (Mute swans, Greylag geese, Ruddy Shelducks, Mandarin ducks and Mallard ducks) that migrate from Asian mainland to Korean Pennisula. All birds became infected. Mute swans and Ruddy Shelducks were the most severely affected, exhibiting 100 percent mortality within 10 days and had the broadest organ distribution of lesions. Greylag geese developed transient nervous system disease while a single Mandarin duck died and had organ lesions most similar to Ruddy Shelducks. The Mallards lacked lesions and were not ill. These results indicate there is significant variation in the ability of this H5N1 HPAI virus to cause disease in different wild waterfowl.

Technical Abstract: The biological outcome of H5N1 high pathogenicity avian influenza (HPAI) virus infection in wild waterfowl is poorly understood. This study examined infectivity and pathobiology of A/chicken/Korea/IS/06 (H5N1) HPAI virus infection in Mute swans (Cygnus olor), Greylag geese (Anser anser), Ruddy Shelducks (Tadorna ferruginea), Mandarin ducks (Aix galericulata) and Mallard ducks (Anas platyrhynchos) following intranasal (IN) inoculation or contact exposure. All birds became infected after either IN-inoculation or contact exposure. Mute swans and Ruddy Shelducks were the most severely affected, exhibiting 100% mortality within 10 days and had the broadest distribution of organ involvement. Pancreas, brain, spleen, heart, oral cavity and adrenal gland were most consistently affected with necrotic and inflammatory changes, and viral antigen was frequently demonstrated in the parenchyma of these organs. In addition, the Mute swans had interstitial pneumonia and hepatic necrosis, and viral antigen was commonly demonstrated in blood vascular endothelial cells throughout the body, hepatocytes, Kupffer cells and pulmonary histiocytes. Greylag geese only exhibited mild neurological signs without mortality, and had residual meningoencephalitis with associated viral antigen at termination. A single contact exposed Mandarin duck died and had a mixture of organ lesions, most similar to Ruddy Shelducks. The Mallards lacked gross and histological lesions, and viral antigen was not demonstrated in any tissues. These results indicate that there is significant variation in the pathobiology of A/Chicken/Korea/IS/06 virus infections in different species of wild waterfowl with Mute swans having strong vascular tropism and the most diverse organ involvement, Ruddy Shelducks and Mandarin ducks having more limited multiple organ involvement, Greylag geese having limited neuropathogenicity, and Mallards having asymptomatic infection without lesions.