Infectious bursal disease virus (IBDV) is a threatening immunosuppressive disease facing poultry industry in Egypt. In this study, detection of very virulent IBDV of twenty broiler flock was shown with high mortalities and bursal lesions from different provinces in Egypt during 2014 (Giza, Dakahleya, Kaliobia and Sharkia). IBDV induces lymphoid cell depletion which can be diagnosed by Immunohistochemistry (IHC). A hyperimmune serum (HS) produced in rabbits through injection of live IBDV vaccine was used as primary antibody in the IHC diagnostic tool. Clinicopathological examination revealed varying bursal lesions from swelling severely inflamed bursal folds filled with whitish exudate to atrophied bursal size. Histopathologically, depletion of bursal lymphoid follicles with hemorrhages and hypercellularity of interfollicular connective tissue were observed. Positive IBDV antigen staining of lymphoid cells population in spleen and bursa of Fabricius was observed by using HS. The obtained HS was validated against standard IBDV antigen by Agar gel immunodiffusion test (AGIDT). The addition of Freund's adjuvant was yielded higher serum protein measured by Nanodrop spectrophotometer. Reverse transcriptase-polymerase chain reaction (RT-PCR) was applied for IBD targeting hypervariable region (HVR) of VP2 gene. The present study concluded to successful validation of produced HS against IBDV antigen and positive intranuclear staining of the lymphoid cell population. Better induction of immune serum total protein produced was obtained by adding adjuvant. RT-PCR for a specific target in VP2 gene was confirmed IBDV infection.