Effects of Host-Dependent Glycosylation of Hemagglutinin on Receptor-Binding Properties of H1N1 Human Influenza A Virus Grown in MDCK Cells and in Embryonated Eggs

Abstract

There is growing evidence that the receptor-binding characteristics of influenza viruses are affected by the host-dependent glycosylation of viral hemagglutinin (HA). To better understand these effects, we propagated two variants of the human influenza virus USSR/90/77 (which differed by the mutation Asn131→ Asp131in the glycosylation sequon of their HA) in either embryonated chicken eggs or MDCK cells. Those variants were then compared for their ability to bind soluble receptor analogs and to attach to receptors represented on a solid phase. The carbohydrate chain at position 131 of the HA (CHO131) interfered with virus binding to soluble Sia2-6Gal-containing macromolecular receptors, but had little or no effect on its binding to Sia2-3Gal-containing macromolecules. This specificity could be explained by the different orientation of the asialic parts of the 2-3-linked sialosides versus 2-6-linked sialosides with respect to the receptor-binding site (Eisenet al.,1997,Virology232, 19–31). In the case of virus attachment to solid-phase immobilized receptors, MDCK-grown viruses bound substantially more weakly than their egg-grown counterparts to receptors of avian origin, whereas binding to mammalian cell membranes was only marginally affected by differences in host-specific glycosylation of the virus. Our data indicate that the effects of the carbohydrate side chains of HA on virus receptor-binding activity are dependent on both the cells in which the virus was grown and the nature of the cellular receptors or intercellular inhibitors to which the virus binds.