title: Genetic diversity and emergence of norovirus GII/4-2006b in Japan during 2006-2007.
abstract: BACKGROUND
  Noroviruses (NoV) are important causes of acute gastroenteritis in infants and young children. This study investigated the prevalence of NoV infections in infants and children with acute gastroenteritis in Japan from July 2006 to June 2007.
  
  
  METHODS
  A total of 628 fecal specimens were collected from infants and children with acute gastroenteritis in five different places (Maizuru, Tokyo, Sapporo, Saga and Osaka), Japan during the period of July 2006 to June 2007. All fecal specimens were examined for NoV by reverse transcription-polymerase chain reaction. Molecular analysis of NoV was carried out by sequencing methods.
  
  
  RESULTS
  From 628 fecal specimens tested, 15.6% (99 of 628) were positive for NoV. Of these, NoV GII most predominant, with a prevalence of 15.5% (97 of 99). Analysis of nucleotide and amino acid sequences revealed that NoVGII strains comprised GII/4 (89%), GII/3 (6.4%), GII/7 (2.3%), and GII/2 (2.3%) genotypes. Among NoVGII/4 strains, all of them belonged to genotype GII/4 2006b variants. Our results clearly indicated that NoV infections were most commonly observed in winter seasons in Japan.
  
  
  CONCLUSIONS
  In conclusion, this study shows the predominance of NoVGII/4 2006b variants and NoV is still burden of disease among Japanese pediatric population.
authors.affiliation: Department of Developmental Medical Sciences, Institute of International Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Shuvra Kanti
authors.initials: SK
authors.lastname: Dey
authors.forename: Tung Gia
authors.initials: TG
authors.lastname: Phan
authors.forename: Masashi
authors.initials: M
authors.lastname: Mizuguchi
authors.forename: Shoko
authors.initials: S
authors.lastname: Okitsu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ushijima
mesh_terms: D000293:Adolescent; D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000821:virology*; D002648:Child; D002675:Child, Preschool; D019143:Evolution, Molecular; D005243:Feces / Q000821:virology; D005260:Female; D005759:Gastroenteritis / Q000453:epidemiology / Q000821:virology; D014644:Genetic Variation; D006801:Humans; D007223:Infant; D007564:Japan / Q000453:epidemiology; D008297:Male; D017720:Molecular Epidemiology; D029322:Norovirus / Q000235:genetics / Q000502:physiology*; D010802:Phylogeny; D015995:Prevalence; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012621:Seasons