DETECTION OF GENETIC VARIATIONS IN SEROTYPE-I ISOLATES OF INFECTIOUS BURSAL-DISEASE VIRUS USING POLYMERASE CHAIN-REACTION AND RESTRICTION-ENDONUCLEASE ANALYSIS

Reverse transcription with polymerase chain reaction (PCR) followed by restriction endonuclease analysis detected genetic variations among s erotype I isolates of infectious bursal disease virus (IBDV). Using a set of synthetic primers derived from the large genome segment of APHI S-IBDV, the hypervariable region (AccI-SpeI fragment) located in the V P2 gene was amplified. With all strains, a cDNA fragment of approximat ely 643 bp was amplified, indicating that there were no apparent delet ions or insertions in this region among isolates. Fragments amplified from 9 isolates were digested with 14 restriction enzymes. Restriction fragment profiles generated by restriction enzymes NaeI, StuI, TaqI, and SacI, showed genetic variations among isolates. This study provide d a simple and sensitive method for detection of genetic variations am ong isolates that are closely related serologically and could not be d ifferentiated using current serologic methods.