title: Single-amino-acid mutation in the HA alters the recognition of H9N2 influenza virus by a monoclonal antibody.
abstract: We explored the molecular basis of antigenic variation by comparing two H9N2 subtype avian influenza viruses, A/Chicken/Shandong/6/96 (CK/SD/6) and A/Chicken/Guangxi/10/99 (CK/GX/10), that react differently to a monoclonal antibody C/B3. To assess the genetic basis for this antigenic difference, we used reverse genetics to generate a series of chimera and mutants of these two viruses. We found that a single-amino-acid substitution of asparagine for serine at position 145 (S145N) in the HA protein prevents the reaction of CK/SD/6 virus with C/B3. Substitution of serine for asparagine at the same position (N145S) enables the CK/GX/10 to react with C/B3 in hemaglutinin inhibition, immunofluorescence and neutralization assays. We further demonstrated that the amino acid N145 in the H9 HA protein is glycosylated. Our results provide experimental evidence that the glycosylation of HA oligosaccharide attachment sites implicated in antibody binding could have a role in antigenic variation.
authors.affiliation: Nangjing Agricultural University, Nanjing 210095, Jiangsu, China.
authors.forename: Jihui
authors.initials: J
authors.lastname: Ping
authors.forename: Chengjun
authors.initials: C
authors.lastname: Li
authors.forename: Guohua
authors.initials: G
authors.lastname: Deng
authors.forename: Yongping
authors.initials: Y
authors.lastname: Jiang
authors.forename: Guobin
authors.initials: G
authors.lastname: Tian
authors.forename: Shuxia
authors.initials: S
authors.lastname: Zhang
authors.forename: Zhigao
authors.initials: Z
authors.lastname: Bu
authors.forename: Hualan
authors.initials: H
authors.lastname: Chen
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology; D000940:Antigenic Variation / Q000235:genetics*; D001216:Asparagine / Q000737:chemistry; D001717:Birds; D002460:Cell Line; D004285:Dogs; D005455:Fluorescent Antibody Technique; D006031:Glycosylation; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000737:chemistry / Q000235:genetics* / Q000276:immunology*; D006801:Humans; D053127:Influenza A Virus, H9N2 Subtype / Q000235:genetics* / Q000276:immunology*; D005585:Influenza in Birds / Q000276:immunology*; D009154:Mutation; D009500:Neutralization Tests; D012694:Serine / Q000737:chemistry
chemical_list: D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D012694:Serine; D001216:Asparagine