title: Clinical and molecular analyses of norovirus-associated sporadic acute gastroenteritis: the emergence of GII.17 over GII.4, Huzhou, China, 2015.
abstract: BACKGROUND
  Noroviruses (NoVs) are the most common cause of non-bacterial acute gastroenteritis (AGE) in all age groups worldwide. The NoVs circulating in Huzhou over the past 7 years were predominantly GII.4 genotypes. In the winter of 2014-2015, a novel variant of NoV GII.17 emerged and became predominant. We report the epidemiological patterns and genetic characteristics of NoV after the appearance of GII.17 in Huzhou City, Zhejiang, China.
  
  
  METHODS
  Between January and December 2015, 746 stool specimens collected from patients with acute gastroenteritis were screened for NoV. Real-time RT-PCR (qPCR) was performed for NoV detection. RT-PCR was used for genomic amplification and sequencing. Genogroups and genotypes were assigned using an online NoV typing tool ( http://www.rivm.nl/mpf/norovirus/typingtool ). Phylogenetic analyses were conducted using MEGA (ver. 6.06).
  
  
  RESULTS
  In total, 196 (26.3%) specimens were identified as NoV-positive. NoV infection was found in all age groups tested (≤5, 6-15, 16-40, 41-60, and ≥60 years), with the 16-40-year age group having the highest detection rate (117/196, 59.7%). Of the 196 NoV-positive specimens, 191 (97.5%) viruses belonged to GII, and 4 (2.0%) to GI; one sample showed GI and GII co-infection. Overall, 117 (59.7%) viruses were sequenced, and new GII.P17/GII.17 variants were the dominant genotype, accounting for 75.2%, followed by GII.Pe/GII.4 Sydney 2012 strains (11.11%). AGE patients infected with the GII.P17/GII.17 genotypes almost all had abdominal pain and watery stools.
  
  
  CONCLUSIONS
  We report the epidemiological patterns and genetic characteristics of the emergence GII.17 over the GII.4 in Huzhou between January and December 2015. After the emergence of GII.17 in October 2014, it steadily replaced the previously circulating GII.4 Sydney 2012 strain, and continued to be dominant in 2015.
authors.affiliation: Huzhou Center for Disease Control and Prevention, Huzhou, 313000, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Huzhou Center for Disease Control and Prevention, Huzhou, 313000, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Chen
authors.affiliation: Huzhou Center for Disease Control and Prevention, Huzhou, 313000, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Fu
authors.affiliation: Huzhou Center for Disease Control and Prevention, Huzhou, 313000, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Ji
authors.affiliation: Huzhou Center for Disease Control and Prevention, Huzhou, 313000, China.
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Wu
authors.affiliation: Huzhou Center for Disease Control and Prevention, Huzhou, 313000, China.
authors.forename: Deshun
authors.initials: D
authors.lastname: Xu
authors.affiliation: Huzhou Center for Disease Control and Prevention, Huzhou, 313000, China. hzcdcwsw@126.com.|Huzhou Center for Disease Control and Prevention, 999 Changxing Road, Huzhou, Zhejiang, 313000, China. hzcdcwsw@126.com.
authors.forename: Jiankang
authors.initials: J
authors.lastname: Han
mesh_terms: D015746:Abdominal Pain / Q000821:virology; D000293:Adolescent; D000328:Adult; D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000209:etiology* / Q000821:virology; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D060085:Coinfection; D003967:Diarrhea / Q000821:virology; D005243:Feces / Q000821:virology; D005260:Female; D005759:Gastroenteritis / Q000453:epidemiology* / Q000209:etiology* / Q000821:virology; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D029322:Norovirus / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D010802:Phylogeny; D060888:Real-Time Polymerase Chain Reaction; D012621:Seasons; D055815:Young Adult
keywords: Acute gastroenteritis; GII.17; Molecular epidemiology; Norovirus