Rapid differentiation between very virulent and classicalinfectious bursal disease viruses isolated in Iran by RTPCR/REA

This study was conducted to characterize infectious bursal disease virus (IBDV) isolatescollected from different parts of Iran during 2005-2006. Pooled bursal samples from 49 broilerand layer pullet flocks suspected to IBD infection were collected and processed. A reversetranscriptase-polymerase chain reaction (RT PCR) procedure was used to amplify a VP2 genefragment (743 bp) from IBDV field isolates. Amplified VP2 fragments were furthercharacterized by two restriction enzymes, BspMI and SacI. From 49 field samples, 37 (75.5%)samples were IBDV positive by RT PCR. Digestion with two restriction enzymes, BspMI andSacI, showed patterns compatible with very virulent IBDV and classical IBDV strains in 34(91.9%) and 3 (8.1%) IBDV-positive samples, respectively. The restriction enzyme analysis ofthis study was comparable to that of other isolates and reference strains with availablenucleotide sequence data in the GenBank. The procedure followed in this study is a usefulmethod to rapidly differentiate the very virulent IBDV and classical IBDV isolates.