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.
|Numero di pagine||9|
|Rivista||Journal of General Virology|
|Stato di pubblicazione||Published - 2015|