Distribution of Influenza Virus Sialoreceptors on Upper and Lower Respiratory Tract in Horses and Dogs

Abstract

It is strongly suspected that equine influenza virus (EIV) is the origin of canine influenza virus (CIV, H3N8), which was first isolated in USA in 2004, on the basis of phylogenetic analyses. Although the distribution of influenza virus sialoreceptors seems to be associated with this interspecies transmission, there is no data of comparisons between the distributions of sialoreceptors on the whole respiratory tract in horses and dogs. We examined the histological distribution of influenza virus sialoreceptors on upper and lower respiratory tract in detail in both animals by double lectin staining with Maackia amurensis (specific for SAα2,3Gal) and Sambucus sieboldiana (specific for SAα2,6Gal). SAα2,3Gal was observed on the surface of ciliated epithelial cells in nasal mucosa, trachea and bronchus in both animals. This result indicated that a dog is susceptible to EIV without alteration of receptor binding specificity.