Experimental infection of greyhounds with equine influenza virus A/Equine/Huabei/01/2007(H3N8).

This investigation assessed the susceptibility of greyhounds to the equine influenza virus(H3N8) that caused outbreak of equine influenza in horse in Northern China.Four greyhounds were infected via intravenously injection,each was inoculated with 1 mL(105.7 EID50) virus cultures,and the other three greyhounds via eye-drop and nose-drop route,each dog was inoculated with 2 mL(2×105.7 EID50).Results showed that all the infected dogs remained clinically healthy and normal body temperature during the observation period.No gross lesions and histopathological changes were observed.At 5 days post inoculation,the M protein of influenza virus was all detected in epithelium cytoplasm of trachea and bronchioles in 4 greyhounds,the virus was recovered and HI antibody was detected respectively in one of infected greyhounds.Seroconversion was demonstrated in 2 serum samples of 3 remaining dogs at 14 days post inoculation.Our data suggested that greyhounds are not susceptible to the A/Equine/Huabei/01/2007(H3N8) isolate,although the virus can infect the greyhound with the massive dose of this virus.Further examination of the presence of influenza virus receptors,sialic acids linked to galactose by an α-2,3 linkage(SAα2,3Gal) or by an α-2,6 linkage(SAα2,6 Gal) in greyhound's respiratory tracts suggested that epithelial surfaces of larynx,trachea,bronchioles contained mainly SAα2,3 Gal,a well-recognized receptors for equine influenza virus,which may partly provided the physio-evidence that the hemagglutination inhibition antibody was induced when the greyhound were infected artificially with equine influenza virus H3N8 subtype.