Examination of macroscopic and microscopic lesions in IBDV-infected organs and molecular characterization of IBDV VP1 gene fragments obtained from commercial broiler farms in Indonesia

Background and Aim: Infectious bursal disease (IBD) is an infectious immunosuppressive that affects young chickens. Instead of strict biosecurity practices, vaccination used to control IBD. However, the has not been effectively managed. Variations in observed clinical symptoms lead confounding diagnoses. The study aimed obtain pathological lesion data from chickens suspected IBD virus (IBDV) infection by gross pathology, confirm IBDV through molecular diagnostics, genotype VP1 gene fragments circulating field. Materials Methods: bursa Fabricius, thymus, spleen, proventricular–ventricular junction, thigh muscles, kidneys samples were collected four commercial broiler farms Central Java Yogyakarta Special Region Province between 2021 2022. examined histopathologically. RNA was extracted Fabricius identified reverse-transcriptase polimerase chain reaction (RT-PCR). RT-PCR positive sample sequenced analyzed Mega X for homology search phylogenetic tree analysis. Results: Macroscopic lesions demonstrated enlarged edema thickened plica, presence gelatinous exudate, hemorrhage, atrophy, caseous exudate lumen. Moreover, thymus had atrophy small gray foci spleen. Petechiae or hemorrhage detected on muscle, kidney dull pale. Hemorrhage junction distinct. histopathological examination showed follicular vacuolization, edema, heterophilic infiltration, congestion, hemorrhage. spleen multifocal necrosis. muscle mucosal part junction. Vacuolization seen renal tubules (nephrosis). Reverse transcriptase-PCR 26 negative 22 samples. Phylogenetic analysis fragment indicated very virulent (vvIBD) belonged B2 genotype. Conclusion: diseases chicken generated macroscopic microscopic primary muscle. Other organs such as kidney, also involved. Molecular confirmed causative agent grouped into vvIBD All vaccinated birds therefore, efficacy available vaccine required urgent evaluation. Since most studies only focused VP1, further exploration VP2 suggested notably new-generation vaccines. Monitoring signs’ transformation over time could assist field diagnostics. Keywords: amplification, genotype, disease, lesions.