Transmission of avian influenza virus (H3N2) to dogs

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From: Emerging Infectious Diseases(Vol. 14, Issue 5)
Publisher: U.S. National Center for Infectious Diseases
Document Type: Article
Length: 3,539 words
Lexile Measure: 1620L

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In South Korea, where avian influenza virus subtypes H3N2, H5N1, H6N1, and H9N2 circulate or have been detected, 3 genetically similar canine influenza virus (H3N2) strains of avian origin (A/canine/Korea/01/2007, A/canine/ Korea/02/2007, and A/canine/Korea/03/2007) were isolated from dogs exhibiting severe respiratory disease. To determine whether the novel canine influenza virus of avian origin was transmitted among dogs, we experimentally infected beagles with this influenza virus (H3N2) isolate. The beagles shed virus through nasal excretion, seroconverted, and became ill with severe necrotizing tracheobronchitis and bronchioalveolitis with accompanying clinical signs (e.g., high fever). Consistent with histologic observation of lung lesions, large amounts of avian influenza virus binding receptor (SA[alpha] 2,3-gal) were identified in canine tracheal, bronchial, and bronchiolar epithelial cells, which suggests potential for direct transmission of avian influenza virus (H3N2) from poultry to dogs. Our data provide evidence that dogs may play a role in interspecies transmission and spread of influenza virus.

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Influenza A virus, a member of the genus Orthomyxovirus, is an economically important virus that causes disease in humans, pigs, horses, and fowl (1). A crucial feature in the ecology and epidemiology of influenza virus is interspecies transmission (2). The emergence of new virus subtypes and their interspecies transmission is of great concern; measures to counteract their spread are vital for preventing influenza epidemics and pandemics. One of the basic mechanisms of interspecies transmission of influenza virus is direct transfer of an essentially unaltered virus from 1 species to another (3); however, some factors restrict this transfer. In particular, the presence or absence of host species--specific influenza virus binding receptors in the upper and lower respiratory tracts serves to prevent such cross-species or zoonotic transmission. Human influenza viruses bind to glycolipids or glycans that contain terminal sialyl-galactosyl residues with [alpha] 2,6-gal linkages (SA[alpha] 2,6-gal), whereas avian influenza viruses bind to residues with SA[alpha] 2,3-gal linkages (4). Examples of interspecies transmission of influenza viruses include recent human infections with the H5N1 subtype of avian influenza virus, and in canine infections with the H3N8 subtype of equine influenza virus (3,5). In addition, influenza infections were recently reported in species (canine, feline) that historically do not carry influenza virus (6). However, most directly transmitted infections of entire influenza viruses from a natural host species to a new host species do not result in sustained transmission in the new host species (3). Therefore, establishing new, long-lived influenza virus lineage is uncommon and difficult (7).

We report interspecies transmission of a complete avian influenza virus (H3N2) to dogs and the emergence of a new canine influenza virus associated with acute respiratory disease in South Korea, where avian influenza viruses (H3N2, H5N1, H6N1, and H9N2) currently circulate or have been previously detected (8). We investigated pathogenicity of the isolated virus in experimental dogs and evaluated localization of SA[alpha] 2,6-gal and SA[alpha] 2,3-gal linkages in upper and lower canine respiratory tracts.

Materials and Methods

Outbreak Histories

From May through September 2007, cases of severe respiratory disease occurred in animals at 3 veterinary clinics located 10-30 km...

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Gale Document Number: GALE|A179029824