title: A new variant of Norovirus GII.4/2007 and inter-genotype recombinant strains of NVGII causing acute watery diarrhoea among children in Kolkata, India.
abstract: BACKGROUND
  Noroviruses (NoVs) are one of the major causal agents of acute gastroenteritis among different age groups. Some of the recent studies reveal that NoV genome is highly prone to mutation and recombination which often leads to emergence of new strains.
  
  
  OBJECTIVE
  To explore the genetic diversity of human Caliciviruses (HuCVs) among diarrhoeic children in Kolkata.
  
  
  METHODS
  The HuCVs were detected by reverse transcription-polymerase chain reaction (RT-PCR) of the partial RNA dependent RNA polymerase gene (RdRp) and capsid gene and confirmed by sequencing. The sequences were analyzed and the recombination point was detected.
  
  
  RESULTS
  Faecal specimens of children (n=111) visiting outpatient department of Dr B. C. Roy Memorial Hospital for Children with acute gastroenteritis were studied: 22 cases were HuCV positive with 21 NoVs. Of these, 12 NoV cases (54.5%) were GII.4 and six cases showed 99% identity with the new variant Japanese strain Hu/NoV/GII.4/OC07138/JP. Three novel NoV GII inter-genotype recombinant strains V1628/IND, V1656/IND and V1737/IND were also detected. The RdRp region of V1628 showed 96% identity with Pont de Roide 673/FRN whereas capsid region resembled GII.7/Osaka F140/JPN strain (98%); the strain V1656 showed 98% identity with RdRp region of GII.4/Monastir 375/TUN but capsid region resembled GII.8/Leverkusen 267/DE (91%); the strain V1737 showed 88% identity with RdRp of GII.5/Minato 6/N1/6/JPN whereas capsid region resembled the GII.12/Gifu 96/JPN (93%). During characterization of Caliciviruses two strains of NoV GII.b and one strain of each NoV GI.1/V1622/06/IND, GI.3/V1707/07/IND, GII.3/V1668/IND, GII.16/V1729/IND, Sapovirus GII.1/V1716/IND were also detected.
  
  
  CONCLUSIONS
  The emergence of new variant of GII.4/2007, three novel NoV GII inter-genotype recombinant strains and various other NoVs, indicates the remarkable genetic diversity of the HuCVs as diarrhoeagenic viruses circulating in Kolkata, India.
authors.affiliation: Molecular Virology Laboratory, Diarrhoeal Disease Research and Control Centre, Division of Virology, National Institute of Cholera & Enteric Diseases, Kolkata, India.
authors.forename: Mukti Kant
authors.initials: MK
authors.lastname: Nayak
authors.forename: Debarati
authors.initials: D
authors.lastname: Chatterjee
authors.forename: S M
authors.initials: SM
authors.lastname: Nataraju
authors.forename: Madhusudan
authors.initials: M
authors.lastname: Pativada
authors.forename: Utpala
authors.initials: U
authors.lastname: Mitra
authors.forename: Mrinal Kanti
authors.initials: MK
authors.lastname: Chatterjee
authors.forename: Tushar K
authors.initials: TK
authors.lastname: Saha
authors.forename: U
authors.initials: U
authors.lastname: Sarkar
authors.forename: Triveni
authors.initials: T
authors.lastname: Krishnan
mesh_terms: D017250:Caliciviridae Infections / Q000453:epidemiology / Q000821:virology*; D002675:Child, Preschool; D016000:Cluster Analysis; D003967:Diarrhea / Q000453:epidemiology / Q000821:virology*; D005243:Feces / Q000821:virology; D005759:Gastroenteritis / Q000453:epidemiology / Q000821:virology*; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D007194:India / Q000453:epidemiology; D007223:Infant; D008969:Molecular Sequence Data; D029322:Norovirus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D010802:Phylogeny; D011995:Recombination, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017385:Sequence Homology