Occurrence and spread of a reassortant very virulent genotype of infectious bursal disease virus with altered VP2 amino acid profile and pathogenicity in some European countries

Metagenomic sequencing determines complete infectious bronchitis virus (avian Gammacoronavirus) vaccine strain genomes and associated viromes in chicken clinical samples

“…The high normalized read counts for this endogenous virus reflect the high host genomic content (90% of trimmed reads) of the pooled tissue sample. Although only reported with a moderate normalized read count, the Avibirnavirus reads detected in the tissue sample pool assembled to a near-complete segment A and 77% of segment B of infectious bursal disease virus, confirming the previously documented circulation in Europe of recombinant strains with a segment A from very virulent and segment B from attenuated IBDV strains [ 74 ]. This finding may be of particular relevance to the observed high IBV genome loads, as IBV disease course can be influenced by IBDV-induced immunosuppression [ 12 , 14 ].…”

The Novel Genetic Background of Infectious Bursal Disease Virus Strains Emerging from the Action of Positive Selection

“…It is also important to highlight that, since the transIBDV has only been detected in Poland, with the exception of Finland in 2014, it is likely that this genetic background emerged in Poland from an undetermined natural source. This hypothesis is supported by recently published results from an IBDV survey conducted in the Netherlands, Belgium, Germany, Denmark, Latvia, the Czech Republic, and Sweden, where the presence of similar reassortants has not been confirmed [55]. In addition, the emergence of strains with a transIBDV-B composition undoubtedly introduces a source of competition in the field, favoring the acquisition of a higher genetic fitness for mutant spectra of the Polish IBDV strains.…”

Research Note: “Hidden” infectious bursal disease virus infections in Central Europe

“…The aforementioned particular reassortant type of IBDVs, circulating in Northern and Western Europe, and in the Czech Republic, was described recently ( Mato et al, 2020 ). These viruses comprise of a vvIBDV type segment A and an attenuated segment B. Reassortants were detected back in 2010 (e.g., 1/chicken/Czech Republic/D1540-1/2010 and 1/chicken/Slovakia/D1588-3-1/2010), and, interestingly, newer reassortant types could be identified in the more recent samples, one of them showing close relation to contemporary Western European strains ( Mato et al, 2020 ). It is challenging to recognize the presence of this type of reassortant viruses because they cause subclinical infections, though bursa atrophy and increased ELISA antibody titers (measured >30 d of age) may be indicative for the circulating IBDV.…”

“…The molecular detection and identification of the viruses as well as the phylogenetic analysis of the partial VP2 and VP1 genes was done as described previously ( Mato et al, 2020 ). Nucleotide sequence data obtained largely a decade ago (from 2010 to 2014) were also involved in order to establish their relationships to the newly detected viruses.…”

“…This situation allows the spread and emergence of different IBDV variants. Recent reports described the currently circulating IBDV strains at different parts of Europe ( Soubies et al, 2017 ; Mato et al, 2020 ; Pikula et al, 2020 ), but there is a lack of information regarding the Central European situation. Therefore, although through a limited number of strains, we provide a snapshot on the diversity of IBDVs collected from the Czech Republic, Slovakia, Hungary, and Serbia over the recent years.…”