HISTOLOGY AND HISTOPATHOLOGY

Cellular and Molecular Biology

 

Localization of influenza virus sialoreceptors in equine respiratory tract

Paola Scocco1 and Vera Pedini2

1Department of Environmental Sciences, University of Camerino, Matelica (MC), Italy and 2Department of Biopathological Sciences and Hygene of animal and food production, University of Perugia, Perugia, Italy.

Offprint requests to: Prof. Paola Scocco, Department of Environmental Sciences, UNICAM, Via Circonvallazione 93-95 62024 Matelica (MC), Italy. e-mail: paola.scocco@unicam.it


Summary. This study was performed to identify the equine respiratory tract areas which express the specific receptor for equine influenza virus; findings may be useful to provide new ways to treat the infectious disease. The present work aims to visualize in situ the presence of sialoderivatives in the horse respiratory tract in order to localize sialoderivatives acting as influenza virus receptors. To this purpose, nasal mucosae, trachea, bronchus and lung parenchyma were removed from 8 mature horses of both sexes. We performed sialic acid characterization by means of mild and strong periodate oxidation and saponification, combined with lectin histochemistry and sialidase digestion, in addition to the direct evidentiation of sialic acid residues. No differences were shown between sexes. Sialic acid residues are present in the nasal mucous cell secretion, where they are linked to galactose by means of α2-3 linkage and are mainly C9 acetylated, and in the nasal and tracheal epithelial lining, where they are represented by periodate labile residues (α2-3)- and/or (α2-6)- linked to galactose. Specific receptors for equine influenza viruses are present at the nasal and tracheal epithelial lining cell coat levels, and in some trachea epithelial cells, but the horse possesses a preventive defence, which consists of the secretion of a mucous layer at nasal level, which could specifically inactivate the hemagglutinins of equine influenza virus; in addition, it expresses other sialoreceptors which can mask the influenza specific ones. Histol Histopathol 23, 973-978 (2008)

Key words: Respiratory tract, Lectin, Sialoderivatives, Influenza virus

DOI: 10.14670/HH-23.973