Molecular characterisation of infectious bursal disease viruses isolated in recent acute outbreaks in Solvenia

Abstract

In 2004 and then in 2006 several outbreaks of infectious bursal disease (IBD) were reported in broiler and broiler breeder flocks in Slovenia. In this report ten recently emerged IBD viruses (IBDV) were characterised by sequence analysis of the VP2 hypervariable region and compared to previous Slovene IBDV strains from 1995/1996 and to some representative serotype 1 IBDV strains of different pathotypes. On the basis of nucleotide and amino acid identities, phylogenetic analyses and the presence of very virulent IBDV (vvIBDV) conserved amino acid substitutions, all Slovene isolates from recent outbreaks were identified as vvIBDV. Although some unique nucleotide exchanges and amino acid substitutions have been observed, the results of this study indicated that recent vvIBDV isolates are closely related with those from outbreaks in the 1990s. However, acute IBD has not been reported in commercial flocks in Slovenia for some years. This could lead to the conclusion that poor biosecurity and relaxed vaccination could be responsible for the re-emergence of vvIBDV.

Phylogeny and evolution of infectious bursal disease virus circulating in Turkish broiler flocks

“…Four very virulent strains (DV86) and one classical strain (HPR2), together with eight vaccine strains, were also detected (Lupini et al, 2016). In Slovenia, phylogenetic analyses of VP2 gene has indicated that recent vvIBDV isolates were closely related to those from outbreaks reported in the 1990s (Rojs et al, 2008). In France, the phylogenetic analyses of the (IBDV) segments A and B of 50 natural or vaccine IBDV strains that were isolated or produced between 1972 and 2002 in 17 countries from four continents, with phenotypes ranging from attenuated to very virulent have shown that 26% of these strains exhibited a significantly different phylogenetic relationship depending on which segment was analysed (Le Nouen et al, 2006).…”