Characterization and pathogenicity of a naturally reassortant and recombinant infectious bursal disease virus in China

Abstract

Infectious bursal disease virus (IBDV), an Avibirnavirus, is the pathogen of infectious bursal disease, which is a severely immunosuppressive disease in 3–15‐week‐old chickens. Different phenotypes of IBDV, including classical, variant, very virulent (vv) and attenuated IBDV, have been reported in many chicken‐rearing countries worldwide. Here, we isolated and identified a naturally reassortant and recombinant IBDV (designated GXB02) from 20‐day‐old chickens with clinicopathological changes of infectious bursal disease (IBD) in Guangxi Province, China. Whole genomic sequencing showed that the strain GXB02 simultaneously has both reassortant and recombinant characteristics with segments A and B being derived from recombinant intermediate vaccine strain and classic strains of IBDV. Segment A of strain GXB02 was incorporated into the skeleton of an intermediate IBDV vaccine strain (W2512), where the breakpoints of two recombinant events located at nucleotide positions 1468 and 1648 were replaced by reassortant vvIBDV (PK2) and vvIBDV (D6948) of segment A, respectively. We used this GXB02 strain to inoculate 21‐day‐old specific‐pathogen‐free chickens to evaluate its pathogenicity. Strain GXB02 has clinicopathologic characteristics of IBD with severe bursal lesions, as evidenced by necrosis, depletion of lymphocytes, and follicle atrophy, indicating that reassortment with classical strains in segment B or/and recombination with very virulent strains increased pathogenicity of the strain GXB02 in chickens. These findings provide important insights into the genetic exchange between classic and attenuated strains of IBDV with two recombinant events occurring at the intermediate derivative segment A with vvIBDV strains, thereby increasing the difficulty of prevention and control of IBD due to novel reassortant–recombinant strains.

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

“…Segmented RNA viruses often show extreme evolutionary dynamics with high gene mutations and reassortment rates, and a few homologous recombinations, allowing dsRNA viruses, including IBDV, to evolve rapidly and adapt to new hosts (Feng et al., 2022; McDonald et al., 2016; Pérez‐Losada et al., 2015). The substitution rate is closely related to virus variation and is a key parameter to understand virus evolution.…”

Phylogenotyping of the Vietnamese infectious bursal disease viruses according to the newly unified genotypic classification scheme

“…The possibility of such reassortment to result in isolates with segment A from the "very virulent" (A3) and segment B derived from the classically attenuated IBDVs (B3) (or vaccines, i.e., from the 002-73 Australian strain) [54] has been well documented, and this co-evolution occurred due to the co-existence of the virulent and attenuated vaccine strains in the eld [20,37,[55][56][57]. Why the A3B3 reassortants have become so virulent and widely spread worldwide, and how the B3 (the early Australian-like B segment) was reassorted with the A3 segment, is a question for further investigation.…”

Alkaloids as potential antivirals. A comprehensive review

“…Both of these viruses cause diseases in animals. IBDV is a retrovirus that can cause a highly contagious disease in young poultry, causing bursal necrosis and severe immune system impairment [ 102 ], while PEDV is an Alphacoronavirus and the primary cause of acute diarrhea, dehydration, and significant mortality in pigs [ 103 , 104 ].…”

“…Both of these viruses cause diseases in animals. IBDV is a retrovirus that can cause a highly contagious disease in young poultry, causing bursal necrosis and severe immune system impairment [102], while PEDV is an Alphacoronavirus and the primary cause of acute diarrhea, dehydration, and significant mortality in pigs [103,104]. Several cyclopeptide alkaloids conjugates were extracted from Ziziphus jujuba Mill., the plant was evaluated against PEDV and it showed strong inhibitory activities in the in vitro antiviral assays.…”