title: Evolutionary characteristics of influenza B virus since its first isolation in 1940: dynamic circulation of deletion and insertion mechanism.
abstract: New antigenic variants of B/Yamagata/16/88-like lineage which appeared in the season of 1997 as a minor strain tended to predominate in the following season. Also, we could observe for the first time, three peaks of activity caused by H3N2 virus and two variants of B influenza virus. Antigenic and phylogenetic analyses revealed that B/Victoria/2/87-like variants appeared again in Japan in 1997 after a nine-year absence. Influenza B viruses evolved into three major lineages, including the earliest strain (I), B/Yamagata/16/88-like variants (II), which comprised of three sublineages (II-(i), II-(ii), II-(iii)), and B/Victoria/2/87-like variants (III). Evolution of influenza B virus hemagglutinin was apparently distinguishable from that of influenza A virus, showing a systematic mechanism of nucleotide deletion and insertion. This phenomenon was observed to be closely related to evolutionary pathways of I, II-(i), II-(ii), II-(iii) and III lineages. It was noteworthy to reveal that the nucleotide deletion and insertion mechanism of influenza B virus completed one cycle over a fifty-year period, and that a three nucleotide deletion was again observed in 1997 strains belonging to lineage II-(iii). It was evident that amino acid substitutions accompanying nucleotide insertions were highly conserved.
authors.affiliation: Department of Virology I, National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Nerome
authors.forename: Y
authors.initials: Y
authors.lastname: Hiromoto
authors.forename: S
authors.initials: S
authors.lastname: Sugita
authors.forename: N
authors.initials: N
authors.lastname: Tanabe
authors.forename: M
authors.initials: M
authors.lastname: Ishida
authors.forename: M
authors.initials: M
authors.lastname: Matsumoto
authors.forename: S E
authors.initials: SE
authors.lastname: Lindstrom
authors.forename: T
authors.initials: T
authors.lastname: Takahashi
authors.forename: K
authors.initials: K
authors.lastname: Nerome
mesh_terms: D000956:Antigens, Viral / Q000032:analysis; D001483:Base Sequence; D005075:Biological Evolution; D003001:Cloning, Molecular; D017353:Gene Deletion; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics*; D006801:Humans; D009981:Influenza B virus / Q000145:classification* / Q000235:genetics / Q000276:immunology; D007251:Influenza, Human / Q000453:epidemiology; D007564:Japan / Q000453:epidemiology; D008969:Molecular Sequence Data
chemical_list: D000956:Antigens, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus