title: Phylogenetic analyses of pandemic influenza A (H1N1) virus in university students at Tobetsu, Hokkaido, Japan.
abstract: Pandemic influenza H1N1 virus (A[H1N1]pdm09) emerged in 2009. To determine the phylogeography of A(H1N1)pdm09 in a single population, 70 strains of the virus were isolated from university students or trainee doctors at Tobetsu, Hokkaido, Japan, between September and December 2009. The nucleotide sequences of the HA1 region of the HA genes and described phylogenetic relationships of the strains circulating among them were analyzed. It was found that the 70 isolates could be phylogenetically separated into three groups and that two epidemics were caused by different groups of the virus. The three groups were also distinguishable from each other by three amino acid changes: A197T, S203T and Q293H. The substitution of S203T, which is located in the antigenic site, suggests antigenic drift of the virus.
authors.affiliation: Department of Microbiology and Immunology, The Research Institute of Personalized Health Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan.
authors.forename: Emi
authors.initials: E
authors.lastname: Inoue
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ieko
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Takahashi
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Osawa
authors.forename: Katsunori
authors.initials: K
authors.lastname: Okazaki
mesh_terms: D019943:Amino Acid Substitution; D016000:Cluster Analysis; D005838:Genotype; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology*; D007564:Japan / Q000453:epidemiology; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D058873:Pandemics; D010802:Phylogeny; D011110:Polymorphism, Genetic; D012367:RNA, Viral / Q000235:genetics; D017422:Sequence Analysis, DNA; D013334:Students; D014495:Universities
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D012367:RNA, Viral