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Epidemiological dynamics of norovirus GII.4 variant New Orleans 2009

  • Autori: Medici, M.; Tummolo, F.; DE GRAZIA, S.; Calderaro, A.; De Conto, F.; Terio, V.; Chironna, M.; Bonura, F.; Pucci, M.; Bányai, K.; Martella, V.; Giammanco, G.
  • Anno di pubblicazione: 2015
  • Tipologia: Articolo in rivista (Articolo in rivista)
  • OA Link:


Norovirus (NoV) is one of the major causes of diarrheal disease with epidemic, outbreak or sporadic patterns in humans of all ages worldwide. NoVs of genotype GII.4 cause nearly 80-90% of all NoV infections in humans. Periodically, some GII.4 strains become predominant generating major pandemic variants. Retrospective analysis of the GII.4 NoV strains detected in Italy between 2007-2013 indicate that the pandemic variant New Orleans 2009 emerged in Italy in the late 2009, became predominant in 2010-2011 and continued to circulate in a sporadic fashion until April 2013. Upon phylogenetic analysis based on the small diagnostic regions A and C, the late New Orleans 2009 NoVs circulating during 2011-2013 appeared genetically different from the early New Orleans 2009 strains that circulated in 2010. For a selection of strains a 3.2-kb-long genome portion at the 3' end was sequenced. In the partial ORF1 and in the full-length ORF2 and ORF3, the 2011-2013 New Orleans NoVs comprised at least three distinct genetic sub-clusters. By comparison with sequences retrieved from the databases, these sub-clusters were also found to circulate globally, suggesting that the local circulation reflected repeated introductions of different strains, rather than local selection of novel viruses. Phylogenetic sub-clustering did not correlate with changes in residues located in predicted putative capsid epitopes, although several changes affected the P2 domain in epitopes A, C, D and E.