Histopathological changes in bursa of broiler birds inoculated with IBD intermediate plus vaccine virus and virulent field IBD virus

The effects of IBD intermediate plus vaccine and virulent field IBD virus on bursa of Fabricius of broiler birds were studied. One group of ten birds was vaccinated with IBD intermediate plus vaccine and another group of birds (10) was infected with field IBD isolates at 12th day of age. Equal number of chicks were kept as untreated controls. All the birds of both the groups were sacrificed on 7th day post vaccination and post infection, accordingly. The pathomorphological changes in the bursa of Fabricius in all the birds were recorded. Histopathologically, the vaccinated group of birds showed severe depletion of lymphocytes in medulla of bursal follicles and birds infected with IBD virulent field isolate showed severe depletion of lymphocytes along with focal lymphoid necrosis, cystic degeneration, haemorrhages and proliferation of interfolicular connective tissue in the bursa of Fabricius. So, the IBD intermediate plus vaccine should be used judiciously as use of this vaccine may lead to vaccine induced immunosupression.