The pathogenesis of H3N8 canine influenza virus in chickens, turkeys and ducks

BACKGROUND Canine influenza virus (CIV) of the H3N8 subtype has emerged in dog populations throughout the United States where it has become endemic in kennels and animal shelters in some regions. It has not previously been determined whether the canine-adapted H3N8 influenza virus can be transmitted to chickens, turkeys or ducks which are economically important animals that are susceptible to type A influenza virus from numerous species. METHODS Four-week-old specific pathogen-free (SPF) chickens, 3-week-old SPF turkeys and 2-week-old commercial Pekin ducks were inoculated with 10(5·2) 50% tissue culture infectious doses of CIV per bird by the intra-choanal route. The birds were observed daily, and at 2 and 4 days post-inoculation (DPI), two inoculated birds and one sham-inoculated control bird were euthanized and necropsied to evaluate gross lesions and to collect tissues for microscopic examination. Cloacal and oral swabs were collected at 2, 4 and 7 DPI to evaluate virus shed by real-time RT-PCR (rRT-PCR). Two weeks post-infection, sera were collected from all remaining birds for type A influenza antibody detection by hemagglutination inhibition assay. RESULTS Clinical signs and gross lesions were not observed in any of the birds of any species nor did any seroconvert. Oral and Cloacal swab material was negative for virus by rRT-PCR. CONCLUSIONS Chickens, turkeys and Pekin ducks are not susceptible to infection with CIV by simulated respiratory exposure route with the dose administered.