Detection and differentiation of infectious bursal disease virus from the outbreaks in two layer farms by PCR-RFLP in Jos, Nigeria

Aim: Characterization of Infectious bursal disease viruses (IBDV) from the two outbreaks in Jos Nigeria, using reverse transcriptase polymerase chain reaction/restriction fragment length polymorphism (RT-PCR/RFLP) technique. Materials and Methods: A total of 40 bursa samples were collected from two outbreaks in November 2011 from two farms of 6-8 weeks old pullets within Jos South Local Government Area, with mortality between 60 – 74.2 % in commercially reared layer chicken flocks experiencing signs typical of infectious bursal disease (IBD). All the samples were found to contain IBDV genome by One Step RT-PCR using VP2 gene specific primers. Result: The assay amplified a 743bp fragment from 701-1444 nucleotides. RT-PCR product was further subjected to restriction digestion using TaqI, MvaI and SacI Restriction enzymes to differentiate classical from very virulent phenotypes. The RFLP profile was found similar for all eight isolates with TaqI and MvaI enzyme but different for SacI. All eight TaqI positive Viruses were further found positive for MvaI digestion and yielded RFLP profile similar to vvIBDV in Europe whereas one isolate was SacI positive and had a RFLP profile similar to classic IBDV strains. Conclusion: The clinical history of high mortality and TaqI and MvaI restriction enzyme positivity revealed that vvIBDV strains still exist in Jos, North central Nigeria.