Molecular characterization of varicella-zoster virus clinical isolates from 2006 to 2008 in a tertiary care hospital, Dublin, Ireland, using different genotyping methods.

Varicella-zoster virus (VZV), a herpesvirus, is a ubiquitous organism that causes considerable morbidity worldwide and can cause severe complications on reactivation. Phylogenetic analysis was performed on 19 clinical VZV isolates (16 zoster and 3 varicella) found in Ireland, between December 2006 and November 2008, in order to determine whether previously reported viral heterogeneity was still present and whether viral recombination was evident. Open reading-frames (ORFs) from genes 1, 21, 50, and 54, were sequenced. Clades 1, 2, 3, and 5 were identified. Four putative recombinant isolates were detected (three clade 3/1 and one clade 5/3/1). Further sequencing and examination of ORF 22 and 21/50, did not elucidate the putative recombinant genotypes further. These two previously published genotyping schemes were examined in light of the new consensus genotyping scheme proposed in 2010. Remarkable VZV heterogeneity remains prevalent in Ireland. This is the first evidence of putative VZV recombination found in Ireland.