Species and age related differences in the type and distribution of influenza virus receptors in different tissues of chickens, ducks and turkeys

Abstract

We undertook one of the most detailed studies on the distribution of α2,3 sialic acid (SA)-galactose (gal) (avian type) and α2,6SA-gal (human type) receptors on different tissues of chickens, ducks and turkeys of varying age groups. On the tracheal epithelium, all 3 bird species expressed strong positive staining (80-90%) for α2,3SA-gal receptors in the 3 different age groups. In addition, a lesser amount of α2,6SA-gal receptors (30-90%) were observed with slight differences in distribution with age and species. The epithelium of the small and large intestine of turkeys and ducks showed negligible staining for α2,6SA-gal receptors whereas the large intestine consistently showed 40-70% positive staining for α2,3SA-gal receptors. In contrast, a greater amount of staining for α2,3SA-gal (50-80%) and α2,6SA-gal (20-50%) receptors were observed along the epithelium of small and large intestine of chickens. Kidney and esophagus sections from the 3 bird species also expressed both avian and human type receptors. In other tissues examined, brain, breast muscles, bursa, spleen, cecal tonsils and oviduct, human type receptors were absent. Though different viral and receptor components may play roles in successful viral replication and transmission, understanding the receptor types and distribution in different tissues of domestic birds might be good initial tool to understand host factors that promote successful influenza viral infection.

Effects of Receptor Binding Specificity of Avian Influenza Virus on the Human Innate Immune Response

“…These types of linkages are frequent in human respiratory epithelia (36). In contrast, the HA of avian strains bind preferentially to ␣2,3-linked sialic acids (SA␣2,3), which are abundant in the avian intestinal tract (33).…”

Receptor Binding Profiles of Avian Influenza Virus Hemagglutinin Subtypes on Human Cells as a Predictor of Pandemic Potential

“…Terminal sialic acid linkage to the penultimate sugar of the glycan chain occurs via carbon 3 or carbon 6, giving the two isomers ␣-2,3 and ␣-2,6 SA, respectively (32). The human upper respiratory tract, the primary site of influenza virus replication in the human host, has abundant SA of the ␣-2,6 isomer, while in the avian gut, the site of replication in avian hosts, the ␣-2,3 conformer predominates, as demonstrated by isoform-specific lectin staining (22,23,38). Among a variety of factors that influence tropism, a major host adaptation facilitating avian influenza virus infection and transmission among humans is mutation in the receptor binding pocket of the HA protein to allow efficient ␣-2,6 SA rather than ␣-2,3 SA binding (19,21,33).…”

Receptor-Binding Profiles of H7 Subtype Influenza Viruses in Different Host Species

“…In particular, these Eurasian poultry influenza viruses displayed good binding to ␣2-6-linked sialic acids (37,53). Studies on expression of sialic acids in intestinal and respiratory epithelia of different birds revealed substantial host-specific distinctions, among them, expression of both Neu5Ac␣2-3Gal-and Neu5Ac␣2-6Gal-terminated sialyloligosaccharides in chicken and quail, in contrast to ducks, which mainly contain Neu5Ac␣2-3Gal in their intestinal epithelium (16,19,23,29,49,63). Taken together, these findings indicated that influenza viruses perpetuated in different birds can have different receptor specificities owing to distinctions in the sialic acid receptors in these avian species.…”