Diagnosis And Molecular Identification Of Virulent Infectious Bursal Disease In Naturally Infected Broiler Chickens.

Infectious bursal disease (IBD) is a serious problem in young chickens and losses occurs in face of restricted biosecurity, frequently vaccination of breeder to maintain uniform high maternal antibody titers and trials to apply more effective vaccines in broiler. The disease was diagnosed based on clinical signs, pathology, and AGPT as well as virus isolation and detection of viral antigen in tissue by RT-PCR. Therefore, bursae were collected from 5 IBD suspected flocks aged 4 to 5 weeks having clinical signs, mortality (35-70%) and lesions suggestive to infected with virulent IBDV. AGP test results showed positive precipitation lines in 5/5tested flocks (100%) between the prepared bursal homogenate or CAM of inoculated ECE with high embryo mortality of virulent IBDV. The 5 bursal homogenate extract were subjected to RT/PCR products of VP2 full gene and electrophoretic pattern of amplified samples revealed the presence of specific PCR products (642 bp). BY restriction end nuclease enzymes BstNI and SspI the samples are negative at 210 bp, 171 bp, 151 bp and 110 bp bands suggested either to be very veriolant IBDV (vvIBDV), while Sspi restriction enzyme analyzed on 2 % agarose gel electrophoresis showed that Results clarify the isolates to be very virulent subtype. The recorded histopathological changes in the examined bursal sections were similar to those previously reported due to infection with veriolant and vvIBDV.Conclusions: We can concluded that virulent IBDV still circulating and cause losses in vaccinated broiler and RTPCR is useful, rapid and accurate in diagnosis IBDV outbreaks.. It is important to look for a more suitable vaccine and vaccination programs for both breeder and broiler chicken to face and controlling very virulent IBDV mutation.