The recombinant origin of emerging human norovirus GII.4/2008: intra-genotypic exchange of the capsid P2 domain.

Department of Zoology, University of Oxford, Oxford, UK.
Journal of General Virology (Impact Factor: 3.53). 01/2012; 93(Pt 4):817-22. DOI: 10.1099/vir.0.039057-0
Source: PubMed

ABSTRACT GII.4 noroviruses are a major cause of acute gastroenteritis in humans. A new variant of GII.4, the 2008 variant, has recently increased its prevalence on a global scale. A previous study of this variant in Japan suggested that it might be of recombinant origin, with a breakpoint at the ORF1-ORF2 junction. Here, examination of the evolutionary origin of the 2008 variant based on a larger sample of worldwide GII.4 norovirus sequences revealed a more complex pattern of recombination between the 2006a- and 2006b-like variants of genotype GII.4, involving the P2 antigenic domain. Double (termed '2008i') and triple (termed '2008ii') recombinant forms of 2008 variants were identified. This study highlights the possible importance of intra-genotypic recombination over antigenic regions in driving norovirus evolution, and is suggestive of a process analogous to the antigenic shift of influenza A virus by reassortment.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Norovirus is one of the major causes of non-bacterial gastroenteritis in humans. The aim of this study was to analyze the amino acid variation of open reading frame 2 of GII.4 variants in South Korea during the period from November 2006 to December 2012. Sixty-nine complete nucleotide sequences of open reading frame 2 were obtained from 113 GII.4 strains. The GII.4 2006b variants were detected predominantly between 2006 and 2009; however, new GII.4 variants, which were termed the 2010 variant and the 2012 variant, emerged in 2010 and 2012, respectively. The number of GII.4 2006b variants steadily decreased until 2012, whereas the number of gastroenteritis cases caused by the new variants increased between 2010 and 2012. The amino acid sequence in the ORF2 region obtained in this study was compared with other GII.4 variants isolated in various countries. Amino acid variations were observed primarily at epitope sites and the surrounding regions. Amino acids 294, 359, 393, and 413 of the P2 subdomain were the most variable sites among the GII.4 variants. The information in this study can be useful in basic research to predict the emergence and determine the genetic functions of new GII.4 variants.
    The Journal of Microbiology 04/2014; 52(5). DOI:10.1007/s12275-014-3538-x
  • [Show abstract] [Hide abstract]
    ABSTRACT: Recombination is an important mechanism generating genetic diversity in norovirus (NoV) that occurs commonly at the NoV polymerase-capsid (ORF1/2) junction. The genotyping method based on partial ORF2 sequences currently used to characterize circulating NoV strains in gastroenteritis outbreaks in Alberta cannot detect such recombination events and provides only limited information on NoV genetic evolution. The objective of this study was to determine whether any NoV GII.4 strains causing outbreaks in Alberta are recombinants. Twenty stool samples collected during outbreaks occurring between July 2004 and January 2012 were selected to include the GII.4 variants Farmington Hills 2002, Hunter 2004, Yerseke 2006a, Den Haag 2006b, Apeldoorn 2007, New Orleans 2009, and Sydney 2012 based on previous NoV ORF2-genotyping results. Near full-length NoV genome sequences were obtained, aligned with reference sequences from GenBank and analyzed with RDPv4.13. Two sequences corresponding to Apeldoorn 2007, and Sydney 2012 were identified as recombinants with breakpoints near the ORF1/2 junction and putative parental strains as previously reported. We also identified, for the first time, a non-recombinant sequence resembling the ORF2-3 parent of the recombinant cluster Sydney 2012 responsible for the most recent pandemic. Our results confirmed the presence of recombinant NoV GII.4 strains in Alberta, and highlight the importance of including additional genomic regions in surveillance studies to trace the evolution of pandemic NoV GII.4 strains.
    Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 07/2014; 27. DOI:10.1016/j.meegid.2014.07.016
  • [Show abstract] [Hide abstract]
    ABSTRACT: Noroviruses are the most common viral agents of acute gastroenteritis in humans. Because noroviruses are very resistant to inactivation, they can lead to public health consequences via the contamination of foods (e. g. molluscs). The aim of this study was to evaluate the prevalence of noroviruses in marine bivalve molluscs sold as food. Standard and real-time reverse transcription-PCR (RT-PCR) procedures were used to monitor bivalve molluscs from the Granada (southern Spain) fish markets for this human enteric virus. Between February 2009 and October 2010 we collected a total of 329 samples of different types of bivalve molluscs (mussels and three types of clam). A total of 329 samples of four species of bivalves were analysed and 23% were positive for noroviruses. Given these results, we conclude that the current processing techniques for bivalve molluscs are ineffective at eliminating their viral load.
    Molluscan Research 05/2014; 34(3):176-180. DOI:10.1080/13235818.2014.888982