Sulfated Glycans Containing Neuac Alpha 2-3gal Facilitate The Propagation Of Human H1n1 Influenza A Viruses In Eggs

When human influenza viruses are isolated and passaged in chicken embryos, variants with amino acid substitutions around the receptor binding site of hemagglutinin (HA) are selected; however, the mechanisms that underlie this phenomenon have yet to be elucidated. Here, we analyzed the receptor structures that contributed to propagation of egg-passaged human H1N1 viruses. The analysis included seasonal and 2009 pandemic strains, both of which have amino acid substitutions of HA found in strains isolated or passaged in eggs. These viruses exhibited high binding to sulfated glycans containing NeuAc alpha 2-3Gal. In MDCK cells overexpressing the sulfotransferase that synthesize Gal beta 1-4(SO3--6)GlcNAc, production of human H1N1 viruses was increased up to 90 fold. Furthermore, these sulfated glycans were expressed on the allantoic and amniotic membranes of chicken embryos. These results suggest that 6-sulfo sialyl Lewis X and/or NeuAc alpha 2-3Gal beta 1-4(SO3--6)GlcNAc are involved in efficient propagation of human H1N1 viruses in chicken embryos.