Molecular detection and sequencing of "Norwalk-like viruses" in outbreaks and sporadic cases of gastroenteritis in Ireland

Norwalk-like viruses (NLVs) are now established as the most important causa tive agents of epidemic gastroenteritis worldwide. The overall objective of this study was to determine the molecular epidemiology of Irish NLV isolat es for the first time by obtaining sequence data from specimens originating from outbreaks and sporadic cases of gastroenteritis. Eight samples from s poradic cases of gastroenteritis and nine isolates from separate NLV outbre aks were examined. Of the sporadic isolates, six were shown to be genogroup 2 (G2) by RT-PCR, while two were G1. All of the outbreak isolates were G2. All isolates were partially sequenced within a highly conserved region of ORF1 (RNA-dependent RNA polymerase gene). Sequence data were aligned and a dendogram was constructed. The results indicated that the majority of G2 is olates were seen to cluster with Bristol and Lordsdale virus, while the two G1 specimens were related most closely to Southampton virus. Further downs tream sequence analysis of a number of the isolates confirmed this result. It is concluded that the majority of NLV isolates circulating in Ireland be long to the Bristol/Lordsdale clade. (C) 2001 Wiley-Liss, Inc.