Deo, IndraKhan, Deena2019-06-222019-06-222005-07http://krishikosh.egranth.ac.in/handle/1/5810109599Bursal homogenates of three infectious bursal disease virus (IBDV) isolates, one from Uttaranchal (UA 5/4) and two from Tamil Nadu (TN 7/4 –A and TN 7/4 –B) were obtained and inoculated in experimental birds. Confirmation of IBDV was done by agar gel precipitation test (AGPT). All the isolates were successfully adapted to chicken embryo fibroblast cells and cytopathic effects (CPE) were observed 48-72 hours post inoculation. Amplification of 643 bp of hypervariable region of VP2 gene of IBDV was done with VP2 specific primers, using RNA isolated from bursal samples of experimentally infected birds and vaccine strain adapted to CEF cells, by reverse transcription polymerase chain reaction (RT-PCR). The restriction fragment length polymorphism (RFLP) was used to compare the amplified region of the VP2 gene among the viruses used in the study. Five restriction enzymes Dra1, Mbo1, Sac1, Ssp1 and Taq1 have been used to determine the molecular group of isolates and vaccine strain. The vaccine strain had pattern similar to that of classical and attenuated strain, which was confirmed by the presence of Sac1 site. The presence of Ssp1 site in UA5/4 in the 643 bp RT-PCR fragment was used to characterize its very virulent (vv) phenotype. TN7/4-A and TN7/4-B also had RE pattern similar to that observed in very virulent type.ennullThesis