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Expression of sialic acid receptors for the binding of avian influenza virus in partridges and pheasants

Georgina Dobek* and Blanca Lupiani
College of Veterinary Medicine and Biomedical Sciences, Texas A&M University.Georgina picture

Objective - To evaluate the potential role of chukar partridges and ring-necked pheasants as intermediate hosts for virus adaptation to chickens and humans, we examined the SA2,6-gal and SA2,3-gal linked influenza virus receptors in the respiratory and digestive tracts of these and other avian species.

Animals – Two chukar partridges, two ring-necked pheasants, five bobwhite quail, three Japanese quail, and four leghorn chickens were used in this study.  All animals were healthy juveniles. 

Procedure – Tissue samples of trachea, lung, colon, and duodenum from each bird were paraffin embedded and sectioned.  Lectin-based staining was performed on tissue sections to identify the type and distribution of these sialic acids.

Results – Staining of partridge and pheasant tissue sections showed a strong positive reaction with MAA lectin specific for 2,3-gal and SNA lectin specific for 2,6-gal receptors.  Quail trachea and chukar partridge trachea exhibited the most 2,6-gal staining of the tissues studied.  Partridge, pheasant, and quail intestinal endothelium stained strong positive for both 2,3-gal and 2,6-gal receptors.  Lung tissue in all species exhibited positive staining for 2,3-gal receptors only.  Chicken tissues only produced positive staining for 2,3-gal receptors. 

Conclusions and Clinical Relevance – These results support the hypothesis that chukar partridges and ring-necked pheasants have the receptors necessary to bind both avian and mammalian influenza viruses.  The results of this study will provide a better understanding of the role these species play in the ecology and evolution of avian influenza viruses.

Impact for Human Medicine – The presence of 2,6-gal receptors in the respiratory and intestinal tract could provide chukar partridges and ring-necked pheasants with the ability to bind human influenza viruses as well as avian influenza viruses.  This may allow these avian species to serve as intermediate hosts for the generation of new influenza viruses with pandemic potential for humans both by genetic shift (reassortment) or genetic drift (point mutations).