In this experiment Intermediate plus strain infectious bursal disease (IBD) vaccine (Inter plus) was used intraocularly on 14 days of age. The progressive rise in QAGPT titre was demonstrated in chicks after detection of first seroconversion by 14 days post IBD vaccination. Further, the Inter plus IBD vaccine showed immunosuppressive effect and residual pathogenicity as evident from lowered HI titres to RD vaccine, poor body weight gain and feed conversion ratio as well as characteristic histopathological changes such as lymphoid necrosis and depletion in bursa of Fabricius in broilers sacrificed 96 hrs post vaccination. The significance of these findings are discussed.
