Antigenic and genetic diversity of early European isolates of Infectious bursal disease virus prior to the emergence of the very virulent viruses: early European epidemiology of Infectious bursal disease virus revisited?

Abstract

Eleven Polish and Hungarian isolates of Infectious bursal disease virus (IBDVs) obtained in the 70/80s (early IBDV) and in the 90s (recent IBDV) were characterized in an Antigen-Capture-ELISA with a panel of neutralizing monoclonal antibodies (Mabs), and by nucleotide sequencing of the VP2 variable domain (vVP2). The viruses were compared with reference IBDV strains, among others with Faragher 52/70 (F52/70, classical, isolated 1970), 89163 (typical very virulent-vvIBDV, isolated 1989) and 91168 (antigenically modified vvIBDV, isolated 1991). Only one of the early isolates (Hungarian strain P1) proved antigenically and genetically similar to F52/70. Other early isolates exhibited no reactivity versus Mabs 3, 4, 5 and/or 8 and had a common previously unrecognized combination of amino acid changes in vVP2. The recent isolates all proved antigenically and genetically related to typical vvIBDV strain 89163, except the Polish isolate 93/35 which proved related to the 91168 strain although no epidemiological relationship had been documented between these viruses in the field. Phylogenetic analysis confirmed that the non-P1 early IBDVs represent a previously unrecognized group among serotype 1 IBDVs. It is discussed whether these early isolates are derivatives of the F52/70-like viruses that might still be present in the field, or whether they represent early IBDV strains that might have been present prior to and progressively replaced by the F52/70-like viruses, as the latter have been replaced by vvIBDVs in the late eighties.

Genetic characterization of South American infectious bursal disease virus reveals the existence of a distinct worldwide-spread genetic lineage

“…Accordingly, the genetic analysis cannot accurately assign this group of viruses, here denoted as dIBDVs, to the typical c, ca, va and vv strains. These Uruguayan and Argentine dIBDVs are included in an independent evolutionary lineage with previously reported viruses from other countries in America (Jackwood & Sommer, 1997;Ikuta et al, 2001;Banda et al, 2003;Remorini et al, 2006;Jackwood & Sommer-Wagner, 2007;Ojkic et al, 2007), Europe (Domanska et al, 2004) and Asia (Kwon et al, 2000) (Figure 2). The hvVP2 Figure 1.…”

“…The isolates 78GsZ and 80GA from Poland appear closely related with the Uruguayan dIBDVs in the VP1 cladogram ( Figure 5), despite being collected nearly four decades ago (Domanska et al, 2004). This result reinforces the similarity between the Uruguayan dIBDVs and the Polish viruses, which had unique genetic and antigenic changes and lowpathogenicity.…”

“…Notably, the Polish 78/GSz and 80/GA and Hungarian P3 and P10 isolates collected from outbreaks during 1975-1981 grouped within the dIBDVs clade in the VP2 phylogeny. These viruses have a singular antigenic profile and belong to a group of six isolates which were suggested to have coexisted and being later displaced by "F52/70-like" viruses before the vvIBDV emergence in Europe (Domanska et al, 2004). Rather than being extinct, our findings suggest that this lineage has been circulating worldwide for decades and is currently coexisting with traditional strains, reaching high prevalence in countries such as Argentina and Uruguay.…”

“…Isolated IBDVs with different traits than the traditional strains have also been sporadically reported through the years in different parts of the world (Ikuta et al, 2001;Domanska et al, 2004;Remorini et al, 2006;Jackwood & Sommer-Wagner, 2007). These IBDVs have been generally considered atypical isolates or variants that have evolved in restricted geographic regions or during short periods of time under particular conditions.…”

Phylogeographic distribution of very virulent infectious bursal disease virus isolates in the Iberian Peninsula

“…Since the usage and availability of nucleic acid sequences have been extended in the veterinary field, numerous studies have characterized IBDV isolates all over the world (i.e., Brown et al, 1994;Etterradossi et al, 2000;Zierenberg et al, 2000;Liu et al, 2002;Rudd et al, 2002;Hernandez et al, 2006) …”