title: Effects of egg-adaptation on receptor-binding and antigenic properties of recent influenza A (H3N2) vaccine viruses.
abstract: Influenza A virus (subtype H3N2) causes seasonal human influenza and is included as a component of influenza vaccines. The majority of vaccine viruses are isolated and propagated in eggs, which commonly results in amino acid substitutions in the haemagglutinin (HA) glycoprotein. These substitutions can affect virus receptor-binding and alter virus antigenicity, thereby, obfuscating the choice of egg-propagated viruses for development into candidate vaccine viruses. To evaluate the effects of egg-adaptive substitutions seen in H3N2 vaccine viruses on sialic acid receptor-binding, we carried out quantitative measurement of virus receptor-binding using surface biolayer interferometry with haemagglutination inhibition (HI) assays to correlate changes in receptor avidity with antigenic properties. Included in these studies was a panel of H3N2 viruses generated by reverse genetics containing substitutions seen in recent egg-propagated vaccine viruses and corresponding cell culture-propagated wild-type viruses. These assays provide a quantitative approach to investigating the importance of individual amino acid substitutions in influenza receptor-binding. Results show that viruses with egg-adaptive HA substitutions R156Q, S219Y, and I226N, have increased binding avidity to α2,3-linked receptor-analogues and decreased binding avidity to α2,6-linked receptor-analogues. No measurable binding was detected for the viruses with amino acid substitution combination 156Q+219Y and receptor-binding increased in viruses where egg-adaptation mutations were introduced into cell culture-propagated virus. Substitutions at positions 156 and 190 appeared to be primarily responsible for low reactivity in HI assays with post-infection ferret antisera raised against 2012-2013 season H3N2 viruses. Egg-adaptive substitutions at position 186 caused substantial differences in binding avidity with an insignificant effect on antigenicity.
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, London, NW7 1AA, UK.|Formerly Divisions of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK.
authors.forename: Lauren
authors.initials: L
authors.lastname: Parker
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, London, NW7 1AA, UK.|Formerly Divisions of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Wharton
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, London, NW7 1AA, UK.|Physical Biochemistry, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Martin
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, London, NW7 1AA, UK.|Formerly Divisions of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK.
authors.forename: Karen
authors.initials: K
authors.lastname: Cross
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, London, NW7 1AA, UK.|Formerly Divisions of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK.
authors.forename: Yipu
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Department of Medicine, Glycosciences Laboratory, Imperial College London, Du Cane Road, London, W12 0NN, UK.
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Medicine, Glycosciences Laboratory, Imperial College London, Du Cane Road, London, W12 0NN, UK.
authors.forename: Ten
authors.initials: T
authors.lastname: Feizi
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, London, NW7 1AA, UK.|Formerly Divisions of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK.
authors.forename: Rodney S
authors.initials: RS
authors.lastname: Daniels
authors.affiliation: Formerly Divisions of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK.|The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, London, NW7 1AA, UK.
authors.forename: John W
authors.initials: JW
authors.lastname: McCauley
mesh_terms: D000220:Adaptation, Biological; D019943:Amino Acid Substitution; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D002645:Chickens; D005289:Ferrets; D006385:Hemagglutination Inhibition Tests; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics / Q000276:immunology; D006801:Humans; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics / Q000254:growth & development / Q000276:immunology* / Q000502:physiology*; D007252:Influenza Vaccines / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D010063:Ovum; D012794:Sialic Acids / Q000378:metabolism; D053585:Virus Attachment; D014776:Virus Cultivation
chemical_list: D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines; D012794:Sialic Acids