Development of probes for differentiation of infectious bursal disease virus strains of various virulence by dot-blot hybridization.

Two different radio-labeled nucleic acid probes, prepared from reverse transcription-polymerase chain reaction (RT-PCR) amplified variable region of VP2 and VP1 gene sequences of a highly virulent infectious bursal disease virus (IBDV), were tested for their ability to detect field isolates of IBDV directly in clinical bursal tissue specimens and vaccine strains of IBDV in tissue cultures. The VP2 gene probe was able to detect both field isolates and vaccine strains of IBDV under high as well as low stringency while the VP1 gene probe could differentiate under high stringency field isolates from vaccine strains, hybridizing only with RNA of field isolates. The sensitivity of both the probes was found to be 4 ng of purified viral RNA.