Identification and Pathogenicity Evaluation of a Novel Reassortant Infectious Bursal Disease Virus (Genotype A2dB3)

Abstract

Infectious bursal disease virus (IBDV) is a non-enveloped, bi-segmented double-stranded RNA virus and the causative agent of a poultry immunosuppressive disease known as infectious bursal disease (IBD). The novel variant IBDV (nVarIBDV) recently posed a great threat to the development of the poultry industry. In this study, we identified a novel segment-reassortant IBDV strain, IBDV-JS19-14701 (Genotype A2dB3). Phylogenic analysis showed that Segments A and B of IBDV-JS19-14701 were derived from emerging nVarIBDV (Genotype A2dB1) and long-prevalent HLJ0504-like strains (Genotype A3B3) in China, respectively. The pathogenicity of IBDV-JS19-14701 was further evaluated via animal experiments. IBDV-JS19-14701 exhibited a similar virulence to chickens with the nVarIBDV. The identification of this reassortment event is beneficial for understanding the epidemiology of nVarIBDV and will contribute to the efficient prevention and control of IBD.

Analysis of the global origin, evolution and transmission dynamics of the emerging novel variant IBDV (A2dB1b): The accumulation of critical aa‐residue mutations and commercial trade contributes to the emergence and transmission of novel variants

“…Global phylogenetic analysis revealed there have been nine well‐supported genogroups of segment A and five genogroups of segment B (Figure 2), consistent with the previous classification (Islam et al., 2021; Y.‐L. Wang et al., 2021). Interestingly, the antigenic variants were clustered into a big genogroup A2, in which A2a, A2b and A2c originated in the United States, while a new lineage A2d (the Chinese nvIBDV) were defined (Figure 2a).…”

“…Phylogenetic analysis showed that all IBDV strains could be divided into 10 well‐supporting genogroups of segment A and five genogroups of segment B as previously described (Islam et al., 2021; Y.‐L. Wang et al., 2021). The segments A and B of nvIBDV were clustered into a single lineage, respectively, and are being defined as a new genotype (A2dB1b), which has been emerging and spreading widely in China and in Asia.…”

“…The widespread emerging nvIBDV may can reassort with the already existed dominant epidemic strain HLJ‐0504‐like in China. For example, new reassortment with v VP2 derived from nvIBDV and VP1 derived from HLJ‐0405‐like has been reported (Wang, Huang, Zhang, et al., 2021; Y. Wang et al., 2021). And it is revealed that this new reassortment phenomenon (A‐nv/B‐HLJ‐0504‐like) can significantly enhance the pathogenicity of nvIBDV (Wang, Huang, Zhang, et al., 2021).…”

“…In addition, a total of 2,679 and 666 sequences of v VP2 and VP1‐b, respectively, were retrieved from GenBank to construct ML trees and screen out all the sequences of avIBDV (including the early US avIBDV and the Chinese nvIBDV) according to the newly proposed classification methods (Islam et al., 2021; Y.‐L. Wang et al., 2021). We eliminated the sequences that are too short (the length of VP2 < 474 bp and VP1 < 767 bp), duplicate or highly similar (nucleotide similarity > 99%), as well as those with vague or incomplete information regarding year and location of detection.…”

“…A new genotypic classification and nomenclature system based on the sequences of both the v VP2 and VP1‐b sampled worldwide has recently been proposed, yielding 10 well‐supported genogroups of segment A (counting the novel genogroup found in Portugal by Legnardi et al., 2022) and five genogroups of segment B (Islam et al., 2021; Y.‐L. Wang et al., 2021).…”