Changing patterns of rotavirus strains circulating in Ireland: re-emergence of G2P[4] and identification of novel genotypes in Ireland.

Worldwide, Group A Rotavirus (RVA) is recognized as the most common aetiological agent of acute diarrheal disease in children. One hundred and ninety seven positive faecal samples were obtained from patients between 2006 and 2008. Reverse transcriptase polymerase chain reaction (RT-PCR) was used to amplify the VP7 and VP4 gene segments of these samples, and G and P typing was carried out subsequently. The most common strain type was G1P[8], and the emergent global G9-type was identified in both years. RVA strain type G2P[4], previously reported in Ireland in 1999, was also detected. Genotypes G2 and G3 in combination with P[4] were detected in 2006-2007 only. There was also an emergence of strain types including G3P[4], G9P[4], G2P[4 + 8] and G2G4P[8] in this study. Molecular analysis of the VP7 genes revealed G1 strains circulating within lineage Ic as previously reported in Ireland. In addition, new sublineage within lineage I of G1 strains was also identified. Analysis of G4 strain NRVL-Hum-49 revealed similarity with other human G4 viruses in lineage Ib. G9 strain NRVL-Hum-74 clustered with a unique G9 strain, CIT-254, in lineage IIIc. This data supports the observations made that the profile of RVA strains in Ireland appears to be dynamic. This study demonstrates that the circulation of human rotavirus is changing continuously in Ireland, and continued surveillance of the circulating strains is needed to detect the appearance of new strains, or new variants which may lead to vaccine breakthrough.