Comparative study of the replication of infectious bursal disease virus in DF-1 cell line and chicken embryo fibroblasts evaluated by a new real-time RT-PCR

A real-time RT-PCR method was developed for the detection of infectious bursal disease virus (IBDV). The VP5 gene of IBDV was chosen as the target binding region for a specific TaqMan probe. The results showed that viral genomic copy number could be quantified accurately ranging from 108 copies/μL to 101 copies/μL. No positive signal was detected for other avian pathogens in the specificity test. This assay was highly sensitive and could detect as little as 30 copies of viral RNA. Both the coefficients of variation (CVs) of inter- and intra-assay reproducibility were less than 2%. Growth curves of the IBDV Gt strain in chicken embryo fibroblasts (CEF) and DF-1 cells were evaluated by the real-time RT-PCR. The data showed that the cytopathic effects of the virus in CEF and DF-1 cells were similar. However, higher viral titers were detected in the DF-1 cell line. This study indicated that the real-time RT-PCR approach provided a powerful diagnostic tool with high sensitivity and specificity for the identification and quantitation of IBDV. The DF-1 cell line may be a more suitable continuous cell line for the propagation of IBDV compared to CEF.