Single-amino-acid mutation in the HA alters the recognition of H9N2 influenza virus by a monoclonal antibody.
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.
Ping
Jihui
J
Nangjing Agricultural University, Nanjing 210095, Jiangsu, China.
Li
Chengjun
C
Deng
Guohua
G
Jiang
Yongping
Y
Tian
Guobin
G
Zhang
Shuxia
S
Bu
Zhigao
Z
Chen
Hualan
H
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
D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D012694:Serine; D001216:Asparagine