title: Molecular epidemiology of noroviruses detected in Nepalese children with acute diarrhea between 2005 and 2011: increase and predominance of minor genotype GII.13.
abstract: Noroviruses, an important cause of acute gastroenteritis, possess a highly divergent genome which was classified into five genogroups and dozens of genotypes. However, changes in genotype distribution over time were poorly understood, particularly in developing countries. We therefore conducted a molecular epidemiological study which characterized the norovirus strains detected in 4437 Nepalese children with acute diarrhea between November 2005 and January 2011 to gain insight into how their genotypes changed over time. Of the 356 samples positive for noroviruses, 277 (78%) were successfully genotyped into 22 capsid genotypes; GII.4 (n=113), GII.3 (n=38) and GII.13 (n=37) were the majority. Interestingly, GII.13 accounted for only 1.7% (4/230) between 2005 and 2008 (period 1) but increased substantially to 26.2% (33/126) between 2009 and 2011 (period 2). Phylogenetic analysis of the VP1 nucleotide sequences of 35 GII.13 strains indicated that they clustered into two lineages named NPL2008 and NPL2009 to which two period 1 strains and 33 period 2 strains belonged, respectively. Lineage NPL2009 contained GII.13 strains that were detected in a large-scale gastroenteritis outbreak in Germany in 2012. Both Nepalese and German VP1 sequences carried two substitutions, H378N and V394Q, in the putative histo-blood group antigen (HBGA)-binding sites. As to the polymerase genotypes of Nepalese strains, the period 1 strains possessed GII.Pm, but the period 2 strains possessed GII.P13, GII.P16, and GII.P21. Together with recent reports on the predominance of GII.P13/GII.13 and GII.P16/GII.13 in India and GII.P16/GII.13 in European countries, this study predicts that genotype GII.13 which was previously regarded as a minor genotype has a potential to become an epidemiologically important genotype.
authors.affiliation: Department of Hygiene and Molecular Epidemiology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Thi Nguyen
authors.initials: TN
authors.lastname: Hoa-Tran
authors.affiliation: Department of Hygiene and Molecular Epidemiology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan; Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, Liverpool, UK.
authors.forename: Toyoko
authors.initials: T
authors.lastname: Nakagomi
authors.affiliation: Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, Sapporo, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sano
authors.affiliation: Tropical Disease Research and Prevention Center, Tribhuvan University, Kathmandu, Nepal.
authors.forename: Jeevan B
authors.initials: JB
authors.lastname: Sherchand
authors.affiliation: Sukra Raj Tropical and Infectious Disease Hospital, Kathmandu, Nepal.
authors.forename: Basu D
authors.initials: BD
authors.lastname: Pandey
authors.affiliation: Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, Liverpool, UK.
authors.forename: Nigel A
authors.initials: NA
authors.lastname: Cunliffe
authors.affiliation: Department of Hygiene and Molecular Epidemiology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan; Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, Liverpool, UK. Electronic address: onakagom@nagasaki-u.ac.jp.
authors.forename: Osamu
authors.initials: O
authors.lastname: Nakagomi
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D001789:Blood Group Antigens / Q000737:chemistry; D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000821:virology*; D036022:Capsid Proteins / Q000737:chemistry / Q000235:genetics; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D003967:Diarrhea / Q000453:epidemiology* / Q000821:virology*; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D009390:Nepal / Q000453:epidemiology; D029322:Norovirus / Q000145:classification / Q000235:genetics*; D010802:Phylogeny; D016415:Sequence Alignment
chemical_list: D001789:Blood Group Antigens; D036022:Capsid Proteins
keywords: GII.13; GII.P16/GII.13; Gastroenteritis; Histo-blood group antigen; Norovirus; Recombination