Identification and molecular characteristics of infectious bronchitis virus isolated from Shanxi Province

ABSTRACT

Chicken infectious bronchitis (IB) is one of the epidemic diseases that cause severe economic loss to poultry industry and induced by the infection of infectious bronchitis virus (IBV). IBV was prone to mutation and recombination due to its genomic characteristics, resulting in new antigenic variants. In order to understand the prevalence and variation of IBV in Shanxi province and provide reference for IB epidemic prevention and control in this area, tissues of a broiler flock suspected of respiratory virus infection were collected in Jinzhong city, Shanxi province. Through PCR identification, chicken embryo inoculation, and sequencing verification, an IBV strain was isolated and named CK/Shanxi-01/2021. On the basis of S1 gene sequencing, the sequence was compared with those of the representative IBV strains of different genotypes deposited in NCBI database, and the phylogenetic tree was constructed. The results of genetic evolution analysis showed that the IBV strain isolated in this study was belonged to GI-19 genotype. The sequence alignment of CK/Shanxi-01/2021 with common IBV vaccine strains H120, M41, H52, 4/91, and LDT3-A showed that the nucleotide homology between the isolated strain and the current common vaccine strain was 78.1%-85.2%, and the amino acid homology was only 75.2%-78.4%. Compared with the sequences of GI-19 genotype strains, some new mutations, including V68I, S120A, A271T, N282T, and N291S, were identified in the S1 protein hypervariable region(HVR). Therefore, it is of great significance for the prevention and control of IB epidemic to strengthen the epidemiological monitoring of IBV and timely grasp the current epidemic IBV genotype and its variation characteristics.