title: Nonimmunoselected intrastrain genetic variation detected in pairs of high-yielding influenza A (H3N2) vaccine and parental viruses.
abstract: Seven influenza A (H3N2) high-yielding vaccine candidate strains were examined. Antigenic analysis revealed that 5 of the strains could be distinguished antigenically from their corresponding wild type parent viruses. Comparative sequence data for the HA1 domains of the HA (hemagglutinin) genes for these 5 high-yielding viruses and the corresponding wild type parents demonstrated one to three amino acid substitutions within each virus pair, with at least one amino acid change being located in a previously defined antigenic site. Comparison of the HA sequences of the 2 antigenically indistinguishable virus pairs revealed no amino acid differences in 1 and one amino acid change in the other. Examination of 1 additional wild type virus, A/Guangdong/39/89, and its three high-yielding derivatives obtained either by serial egg passage or by reassortment revealed an additive effect of the HA and M genes in creating the high-yielding phenotype.
authors.affiliation: Influenza Branch, Centers for Disease Control and Prevention, Atlanta, Georgia 30333.
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.forename: E D
authors.initials: ED
authors.lastname: Kilbourne
authors.forename: H E
authors.initials: HE
authors.lastname: Hall
authors.forename: N J
authors.initials: NJ
authors.lastname: Cox
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D005814:Genes, Viral / Q000235:genetics*; D014644:Genetic Variation / Q000235:genetics*; D006385:Hemagglutination Inhibition Tests; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D006389:Hemagglutinins, Viral / Q000235:genetics*; D006801:Humans; D053122:Influenza A Virus, H3N2 Subtype; D009980:Influenza A virus / Q000235:genetics*; D007252:Influenza Vaccines / Q000235:genetics; D008969:Molecular Sequence Data; D012367:RNA, Viral / Q000235:genetics; D016865:Reassortant Viruses / Q000235:genetics*; D017422:Sequence Analysis, DNA; D015678:Viral Structural Proteins / Q000235:genetics*
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D006389:Hemagglutinins, Viral; D007252:Influenza Vaccines; D012367:RNA, Viral; D015678:Viral Structural Proteins