title: [Mutations of the hemagglutinin gene of H9N2 subtype avian influenza viruses under selective pressure of antibody].
abstract: OBJECTIVE
  To understand mutations of avian influenza virus (AIV) under the antibody selective pressures.
  
  
  METHODS
  We continuously passed an H9N2-AIV strain LG1 in embryos with or without maternal antibody to LG1 in 6 separate serials. At the 10th, 20th, 30th, 40th and 50th passages in each serial, H9 hemagglutinatin gene (HA) sequences were determined and compared to the original LG1 strain.
  
  
  RESULTS
  Only unstable random mutations happened in 29 sites with nonsynonymous vs synonymous (N/S) mutation ratio of 1.42 during 50 passages in 2 serials without maternal antibodies. However, multiple stable nonsynonymous mutations were detected gradually during 50 passages of 4 serials in embryos with maternal antibody to LG1 strain, and the NS/S ratio was as high as 3.46 among 45 mutated sites.
  
  
  CONCLUSIONS
  The results suggested that the antibody selective pressure influenced mutations of H9N2 AIV HA gene during the passages in embryos with maternal antibody. Embryos with maternal antibody to certain viruses could be used as experimental models to study the immune selective pressures on viral mutations.
authors.affiliation: College of Animal Science and Technology, Shandong Agricultural University, Tai'an 271018, China.
authors.forename: Benhong
authors.initials: B
authors.lastname: Lou
authors.forename: Xiutong
authors.initials: X
authors.lastname: Zhu
authors.forename: Beibei
authors.initials: B
authors.lastname: Sun
authors.forename: Zhizhong
authors.initials: Z
authors.lastname: Cui
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology*; D002642:Chick Embryo; D002645:Chickens; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics* / Q000276:immunology; D053127:Influenza A Virus, H9N2 Subtype / Q000235:genetics* / Q000276:immunology; D005585:Influenza in Birds / Q000276:immunology* / Q000821:virology; D009154:Mutation; D012641:Selection, Genetic
chemical_list: D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus