Genetic Insight into the Interaction of IBDV with Host-A Clue to the Development of Novel IBDV Vaccines

Abstract

Infectious bursal disease virus (IBDV) is an immunosuppressive pathogen causing enormous economic losses to the poultry industry across the globe. As a double-stranded RNA virus, IBDV undergoes genetic mutation or recombination in replication during circulation among flocks, leading to the generation and spread of variant or recombinant strains. In particular, the recent emergence of variant IBDV causes severe immunosuppression in chickens, affecting the efficacy of other vaccines. It seems that the genetic mutation of IBDV during the battle against host response is an effective strategy to help itself to survive. Therefore, a comprehensive understanding of the viral genome diversity will definitely help to develop effective measures for prevention and control of infectious bursal disease (IBD). In recent years, considerable progress has been made in understanding the relation of genetic mutation and genomic recombination of IBDV to its pathogenesis using the reverse genetic technique. Therefore, this review focuses on our current genetic insight into the IBDV's genetic typing and viral genomic variation.

Keywords: genetic evolutionary typing; infectious bursal disease virus (IBDV); reverse genetic; viral genome diversity.

Figure 1

Concise circular phylogenetic analysis based on the VP2 hypervariable region of IBDV segment A. The analysis of 56 IBDV strains was performed using MEGA X [102] with the maximum likelihood method, and 1000 bootstrap replications were included. The tree was annotated in iTOL (https://itol.embl.de, accessed on 3 March 2023) and drawn to scale, with genogroup information displayed in colored circular stripes on the outermost ring. The names and GenBank accession numbers of the strains are shown in the figure. The novel variant strains recently reported belonging to the A2 are shown in red bold.

Figure 2

Concise circular phylogenetic analysis based on the “B marker region” of IBDV segment B. The analysis of 71 IBDV strains was performed using MEGA X [102] with the maximum likelihood method, and 1000 bootstrap replications were included. The tree was annotated in iTOL (https://itol.embl.de, accessed on 3 March 2023) and drawn to scale, with genogroup information displayed in colored circular stripes on the outermost ring. The names and GenBank accession numbers of the strains are shown in the figure. The novel variant strains recently reported belonging to the B1 are shown in red bold.

Figure 3

Ribbon diagram of the predictive structure of IBDV VP2. The Protein Data Bank accession code is PDB-7VRP [115]. The VP2 subunit is folded into three domains: P domain (red), S domain (yellow), and B domain (blue). The right side of the figure shows the β-sheets of the P domain, with the four loops marked in different colors and the names in uppercase letters. The figure was generated using PyMOL (The PyMOL Molecular Graphics System) [116].