Transmission and pathogenicity of canine H3N2 influenza virus in dog and guinea pig models.

BACKGROUND: Influenza A virus causes respiratory disease in many animal species as well as in humans. Due to the high human-animal interface, the monitoring of canine influenza in dogs and the study of the transmission and pathogenicity of canine influenza in animals are important. METHODS: Eight-week-old beagle dogs (Canis lupus familaris) (n = 13) were used for the intraspecies transmission model. The dogs were inoculated intranasally with 1 ml of 106 EID50 per ml of canine H3N2 influenza virus (A/canine/Thailand/CU-DC5299/2012) (CIV-H3N2). In addition, 4-week-old guinea pigs (Cavia porcellus) (n = 20) were used for the interspecies transmission model. The guinea pigs were inoculated intranasally with 300 µl of 106 EID50 per ml of CIV-H3N2. RESULTS: For the Thai CIV-H3N2 challenged in the dog model, the incoculated and direct contact dogs developed respiratory signs at 2 dpi. The dogs shed the virus in the respiratory tract at 1 dpi and developed an H3-specific antibody against the virus at 10 dpi. Lung congestion and histopathological changes in the lung were observed. For the Thai CIV-H3N2 challenge in the guinea pig model, the incoculated, direct contact and aerosol-exposed guinea pigs developed fever at 1-2 dpi. The guinea pigs shed virus in the respiratory tract at 2 dpi and developed an H3-specific antibody against the virus at 7 dpi. Mild histopathological changes in the lung were observed. CONCLUSION: The result of this study demonstrated evidence of intraspecies and interspecies transmission of CIV-H3N2 in a mammalian model.

Evidence of pandemic H1N1 influenza exposure in dogs and cats, Thailand: A serological survey.

Influenza A virus causes respiratory disease in both humans and animals. In this study, a survey of influenza A antibodies in domestic dogs and cats was conducted in 47 animal shelters in 19 provinces of Thailand from September 2011 to September 2014. One thousand and eleven serum samples were collected from 932 dogs and 79 cats. Serum samples were tested for influenza A antibodies using a multi-species competitive NP-ELISA and haemagglutination inhibition (HI) assay. The NP-ELISA results showed that 0.97% (9/932) of dogs were positive, but all cat samples were negative. The HI test against pandemic H1N1, human H3N2 and canine H3N2 showed that 0.64% (6/932) and 1.20% (1/79) of dogs and cats were positive, respectively. It is noted that all six serum samples (5 dogs and 1 cat) had antibodies against pandemic H1N1. In summary, a serological survey revealed the evidence of pandemic H1N1 influenza exposure in both dogs and cats in the shelters in Thailand.