Molecular Characterization, Adaptation and Attenuation of Locally Isolated and Vaccinal Strain of Infectious Bursal Disease Virus for Development of Vero Cell-Based Infectious Bursal Disease Vaccine in Ethiopia

Infectious Bursal Disease (IBD) or Gumboro Disease is one of the most common diseases of commercial poultry in Ethiopia.Vaccination is the principle method to control the disease. Currently, NVI is producing IBD vaccine by using standard strains of IBDV on primary chicken embryo blast in Ethiopia.  But the production of live attenuated IBD vaccine from locally isolated IBDV stain provides high protection for chickens against field IBDV strains. IBD vaccine production on primary chicken embryo blast is also very laborious, time consuming and economically costy. However, production of live attenuated IBD vaccine using Vero cell can solve these issues. The present study was initiated to propagate, adapt, and attenuate both locally isolated and commercially available IBDV strains in the vero cell lines for development of an effective Vero cell-based IBD vaccine in Ethiopia. Locally isolated and LC-75 vaccinal strain IBDVs were successfully adapted and attenuated in Vero-cell line in NVI and molecularily characterized. The IBDV virus strains were attenuated by further serial passages and pathogenicity test at specific passages were conducted in breeder chickens free from antibodies against IBDV to evaluate the loss of virulence in the virus during passaging on Vero cell line. Vero cell could be used as a model to study the growth of kinetic of the IBDV isolate and the Vero adapted attenuated virus should be further studied for possible adoption as a candidate for an attenuated IBD vaccine development. Keywords: Chicken, Immunosuppression, Infectious bursal disease, Infectious Bursal Disease Virus, Isolation, Molecular characterization, Vaccination, Vero cell.