Molecular Characterization of Iranian Infectious Bursal Disease Viruses

Abstract

This study was conducted to characterize nine infectious bursal disease virus (IBDV) isolates from Iran. A reverse<br><br>transcriptase–polymerase chain reaction (RT-PCR) procedure was used to amplify a 743-bp fragment of the VP2 gene<br><br>hypervariable region from IBDV field isolates. Amplified VP2 fragments of the nine IBDV isolates were sequenced and compared<br><br>with published sequences of IBDV strains from Iran and around the world, and their phylogenetic relationships were analyzed.<br><br>Three isolates demonstrated close relation to classical attenuated strains of IBDVs, and six isolates showed sequences common in<br><br>European and Asian strains of very virulent IBDVs (vvIBDVs). Four nucleotide changes—802A, 934A, 940A, and 1366A—were<br><br>common in all Iranian vvIBDVs except in one isolate. Amino acid sequences of three Iranian vvIBDVs were 100% identical and<br><br>resembled vvIBDV strains from European (UK661), Asian (HK46, GZ96), and Iranian origins (IR01, SDH1). Some unique<br><br>amino acid substitutions after major hydrophilic peak A in Iranian vvIBDV field isolates were observed: 231S-L, 231S-P, and<br><br>233N-K. Phylogenetic analysis showed that the Iranian vvIBDVs were closely related to European and Asian vvIBDVs. Further<br><br>comprehensive investigations will provide more information on the distribution, variability, and phylogenetic relationships of<br><br>different IBDVs isolated in Iran and other parts of the world.