title: Genetic and epidemiological analysis of influenza virus epidemics in Taiwan during 2003 to 2006.
abstract: The genetic characterization of Taiwanese influenza A and B viruses on the basis of analyses of pairwise amino acid variations, genetic clustering, and phylogenetics was performed. A total of 548, 2,123, and 1,336 sequences of the HA1 genes of influenza A virus subtypes H1 and H3 and influenza B virus, respectively, collected during 2003 to 2006 from an island-wide surveillance network were determined. Influenza A virus H3 showed activity during all periods, although it was dominant only in the winters of 2002-2003 and 2003-2004. Instead, influenza B virus and influenza A virus H1 were dominant in the winters of 2004-2005 and 2005-2006, respectively. Additionally, two influenza A virus H3 peaks were found in the summers of 2004 and 2005. From clustering analysis, similar characteristics of high sequence diversity and short life spans for the influenza A virus H1 and H3 clusters were observed, despite their distinct seasonal patterns. In contrast, clusters with longer life spans and fewer but larger clusters were found among the influenza B viruses. We also noticed that more amino acid changes at antigenic sites, especially at sites B and D in the H3 viruses, were found in 2003 and 2004 than in the following 2 years. The only epidemic of the H1 viruses, which occurred in the winter of 2005-2006, was caused by two genetically distinct lineages, and neither of them showed apparent antigenic changes compared with the antigens of the vaccine strain. For the influenza B viruses, the multiple dominant lineages of Yamagata-like strains with large genetic variations observed reflected the evolutionary pressure caused by the Yamagata-like vaccine strain. On the other hand, only one dominant lineage of Victoria-like strains circulated from 2004 to 2006.
authors.affiliation: Department of Medical Biotechnology and Laboratory Science, Chang Gung University, 259 Wen-Hua 1st Road, Kweishan, Taoyuan, 333 Taiwan, Republic of China.
authors.forename: Jhih-Wei
authors.initials: JW
authors.lastname: Jian
authors.forename: Guang-Wu
authors.initials: GW
authors.lastname: Chen
authors.forename: Cheng-Tsung
authors.initials: CT
authors.lastname: Lai
authors.forename: Li-Ching
authors.initials: LC
authors.lastname: Hsu
authors.forename: Pei-Jer
authors.initials: PJ
authors.lastname: Chen
authors.forename: Steve Hsu-Sung
authors.initials: SH
authors.lastname: Kuo
authors.forename: Ho-Sheng
authors.initials: HS
authors.lastname: Wu
authors.forename: Shin-Ru
authors.initials: SR
authors.lastname: Shih
mesh_terms: D004196:Disease Outbreaks; D014644:Genetic Variation; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000145:classification / Q000235:genetics*; D053122:Influenza A Virus, H3N2 Subtype / Q000145:classification / Q000235:genetics*; D009981:Influenza B virus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D008969:Molecular Sequence Data; D010802:Phylogeny; D012621:Seasons; D017422:Sequence Analysis, DNA; D013624:Taiwan / Q000453:epidemiology
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; C493831:hemagglutinin HA1, influenza B virus