Vaccination of chickens with the naturally attenuated YC_GVI-1 strain conferred complete protection (100%) against the heterologous JS96_GI-19 strain.
The naturally attenuated YC_GVI-1 strain induces strong humoral immunity and provides complete protection against the heterologous JS96_GI-19 strain in chickens, offering potential for vaccine development.
Infectious bronchitis virus (IBV) causes a highly contagious disease in chickens. The prevalence of GVI-1 is increasing; however, the genomic characteristics and antigenic properties of this genotype strain remain insufficiently characterized. In this study, the genome characteristics and antigenic properties of a naturally attenuated CK/CH/SC/YCGVI-1-DK/LMB20210104 (abbreviated as YCGVI-1) strain were systematically analyzed. YCGVI-1 occupies a distinct phylogenetic lineage and shares a similarity of 98. 2%, the highest nucleotide sequence homology, with the reference strain CK/CH/FJ/202005 (accession number: MW791835. 1). This strain was likely originated through a genetic recombination event between two major parental strains, CK/CH/FJ/202005 and CK/CH/GX/HX (accession number: PP817796. 1). However, its S protein harbors ten unique amino acid substitutions, compared to the same protein in the other two virulent strains in the same genotype. AlphaFold3-based structural prediction reveals that one of these substitutions, methionine 485 to valine substitution, may induce a conformational change in the adjacent phenylalanine residue at position 431, resulting in a shift in the local secondary structure from β-sheet to random coil. Characterization of its antigenicity showed that this strain induces a strong humoral immune response, with neutralizing antibody titers of 26. 40 against homologous strain YCGVI-1 and 24. 00 against heterologous strain JS96GI-19. Furthermore, vaccination of chickens with this strain conferred complete protection (100%) against JS96GI-19. The findings provide novel insights into the molecular evolution and antigenicity of YCGVI-1, offering key information for improving IBV surveillance and vaccine development.
Xiong et al. (Fri,) conducted a other in Infectious bronchitis virus (IBV). Vaccination with naturally attenuated YC_GVI-1 strain was evaluated on Protection against JS96_GI-19. Vaccination of chickens with the naturally attenuated YC_GVI-1 strain conferred complete protection (100%) against the heterologous JS96_GI-19 strain.