Molecular Identification of IBDV from Naturally Infected Chicken Flocks

Our study was performed to molecularly identify infectious bursal disease (IBD) virus (IBDV) from naturally infected native chickens. Thus, bursa specimens were collected from two IBD vaccinated native broiler chicken flocks showing clinical signs, mortality and lesions of IBD in this study. The collected bursae showed pathological changes related to those of IBD infection. Furthermore, the isolates were molecularly characterized using reverse transcription polymerase chain reaction (RT-PCR) technique and gene sequencing of partial portion of VP2 gene. The two isolates (Genbank accession numbers MW925051 and MW9250522) were characterized as very virulent IBDV (vvIBDV). The obtained nucleotide sequences of partial portion of VP2 gene of 2 isolates revealed 97.0 -100% and 91.2-92.5% identity with the Egyptian strains and vaccine strains respectively. Finally, significant genetic changes in our IBDV isolates were observed as comparing to vaccine strains. Thus, continuous monitoring of IBDV outbreaks in vaccinated chickens and evaluation of the used vaccines are required.