Differentiation of infectious bronchitis virus vaccine strains Ma5 and 4/91 by TaqMan real-time PCR

The aim of this study was to develop rapid molecular assays for differentiating vaccine strains Ma5 and 4/91 of the infectious bronchitis virus (IBV). Specific primers and probes for S1 and N genes were designed based on the nucleotide sequences of both vaccine strains. Cross-reactivity was not observed. Assay sensitivity was 2.373 × 103 copies of the Ma5 strain, and 3.852 x 103 copies of the 4/91 strain. Samples belonging to a known genotype demonstrated that the designed assays supported rapid and sensitive detection of Ma5 and 4/91 vaccine strains of IBV.