Summary. – Infectious bursal disease (IBD) is a highly contagious disease of chickens caused by Infectious bursal disease virus (IBDV). In turkeys, however, infection with classical virulent IBDV strains lead only to subclinical forms of the disease. We attempted to isolate IBDV from the bursa of turkey and characterize it. Amplification of a 743-bp fragment of VP2 gene by RT-PCR and restriction analysis of the product showed a pattern compatible with very virulent IBDV (vvIBDV). Comparison of the sequence of this isolate with those of other IBDVs and phylogenetic analysis confirmed very virulent nature of the isolate. This is the first report on the isolation of vvIBDV from turkey in Iran.

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