Assessment of genetic, antigenic and pathotypic criteria for the characterization of IBDV strains

Abstract

The aim of this work was the selection and comparison of representative infectious bursal disease virus (IBDV) strains. Nine strains of IBDV, isolated at different times and from different geographic regions of Europe and China, were characterized. Batches of all strains were prepared following standardized protocols and checked for the absence of contaminating viruses. Criteria used for their characterization were: (i) the nucleotide sequence of the VP2 variable region, (ii) binding to a panel of neutralizing monoclonal antibodies in antigen capture enzyme-linked immunosorbent assays, and (iii) virulence in specific pathogen free chickens after infection with a standardized number of median embryo infective doses. Based on the first two criteria, two of nine strains were classified as classical virulent (cv) IBDV (F52/70, Cu-1wt), and five as very virulent (vv) IBDV (849VB, 96108, HK46, GX, Harbin). Remarkably, although a clear-cut difference was demonstrable between European cvIBDV (F52/70 and Cu-1wt) and vvIBDV (849VB and 96108) strains, there was a continuum in the pathogenicity of Chinese vvIBDVs. Our results indicate the probable existence of differences in virulence within IBDV lineages determined on the basis of antigenic typing using monoclonal antibodies and the alignment of the VP2 sequences. This indicates limitations in the analysis of IBDV pathotypes based on the VP2 variable region and emphasizes that these criteria may not be sufficient for the classification of IBDV strains.

Protection Effect of Vaxxitek HVT + IBD Vaccine Against Infectious Bursal Disease in Broiler Chickens

“…At the end of the 1980s, antigenic variants in the United States of America and very virulent (vv) IBDV strains in Europe (antigenically similar to the "classical strains") emerged in vaccinated flocks and rapidly spread all over the world. The vvIBDV can cause 100% mortality in experimentally infected specific pathogen free (SPF) chickens, and mortality rates of 60% and 30% have been reported in layers and broilers respectively in field conditions (Van den Berg et al, 2004 andVan den Berg et al, 1991).…”

In vitrocharacterization of chicken bone marrow-derived dendritic cells following infection with very virulent infectious bursal disease virus

“…However, very virulent strains generally cause severe and acute pathological effects, as well as higher mortality, compared to the classical strains (Williams & Davison, 2005). In addition, typical very virulent strains may cause up to 100% mortality in specific-pathogen-free chickens (van den Berg et al, 2004). Meanwhile, mild and vaccine strains do not cause mortality or clinical signs, but bursal lesions are dependent on the virulence of the virus (Rautenschlein et al, 2005).…”

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

“…Some recent studies indicate limitations in the analyses of IBDV pathotypes based on the VP2 variable region and emphasise that this criterion may not be sufficient for the classification of IBDV strains (Boot et al, 2000;van den Berg et al, 2004). Based on the high molecular similarity and the compatible field clinical features, Slovene strains are expected to belong to the very virulent phenotype.…”