title: Seasonal distribution and genetic diversity of genogroups I, II, and IV noroviruses in the Tamagawa River, Japan.
abstract: We investigated the prevalence, seasonal dependence, and genetic diversity of noroviruses (NoVs) in the Tamagawa River, which runs through a densely populated region in Tokyo, Japan, from April 2003 to March 2004. A total of 60 water samples were collected from five sites from upstream to downstream along the river, and 500 mL of which was concentrated using the "cation-coated filter method". Of the 60 samples tested, genogroup I (GI) and GII NoVs were detected from 28 (47%) and 18 (30%) samples, respectively. GIV NoV was successfully detected from 2 (3%) samples with a newly developed seminested RT-PCR assay specific for GIV. The occurrence of NoVs in the river was significantly higher in winter/spring than in summer/autumn and also in mid- to downstream rather than upstream. A total of 176 different NoV strains were identified from river water samples based on the phylogenetic analysis of partial capsid gene sequences. GI, GII, and GIV strains were clustered into 7 (GI/1, 2, 4, 5, 8, 9, and 11), 8 (GII/2, 3, 4, 5, 6, 11, 12, and 16), and 1 (GIV/1) genotypes, respectively. The results suggest that genetically diverse NoV strains are circulating between human populations and aquatic environments.
authors: Department of Urban Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan. kitajima@env.t.u-tokyo.ac.jp.
authors: Masaaki
authors: M
authors: Kitajima
authors: Tomoichiro
authors: T
authors: Oka
authors: Eiji
authors: E
authors: Haramoto
authors: Naokazu
authors: N
authors: Takeda
authors: Kazuhiko
authors: K
authors: Katayama
authors: Hiroyuki
authors: H
authors: Katayama
mesh_terms: D001483:Base Sequence; D002213:Capsid / Q000378:metabolism; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D007564:Japan; D008969:Molecular Sequence Data; D029322:Norovirus / Q000235:genetics*; D010802:Phylogeny; D045483:Rivers / Q000821:virology*; D012621:Seasons