Molecular Characterization, Attenuation, and Safety Testing of Very Virulent Infectious Bursal Disease Virus as an Active Infectious Bursal Disease Vaccine Candidate

Infectious bursal disease (IBD) is a significant viral infection in poultry caused by infectious bursal disease virus, resulting in immunosuppression and economic losses. The development of a safe and effective vaccine, particularly for very virulent infectious bursal disease virus (vvIBDV), is crucial for mitigating its impact. This study aimed to molecularly characterize, attenuate, and evaluate the safety of selected very virulent infectious bursal disease virus strains for potential vaccine development. The virus, previously confirmed as very virulent infectious bursal disease virus, was attenuated through serial passages in specific pathogen-free embryonated chicken eggs. Molecular characterization was conducted via reverse transcription-polymerase chain reaction and sequencing of the VP2 gene. The safety evaluation included vaccinating specific pathogen-free chickens with a 10-dose regimen and determining the index of the bursal body weight ratio. The virus exhibited successful attenuation after 40 serial passages, resulting in reduced pathogenicity and stable mortality rates. Molecular analysis revealed the genetic stability of the VP2 gene during the attenuation process. The index of the bursal body weight ratio values exceeded the safety standards established in the Indonesian Veterinary Pharmacopoeia, confirming the safety of the strain for further vaccine development. This study demonstrated that the attenuated very virulent infectious bursal disease virus strain is a promising candidate for vaccine development, combining genetic stability, reduced pathogenicity, and safety in specific pathogen-free chickens. These findings provide a foundation for further evaluation of the strain as a potential vaccine seed.

Cite this article as: Utami, Y. M., Pratomo, A. A., Kusumastuti, A., Utomo, R. R., Nurhandayani, A., Ong, S., Roza, S., & Wibowo, M. H. (2026). Molecular characterization, attenuation, and safety testing of very virulent infectious bursal disease virus as an active infectious bursal disease vaccine candidate. Acta Veterinaria Eurasia, 52, 0129, doi:10.5152/actavet.2026.25129.