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The aim of this study was to investigate when it was possible to detect infectious bursal disease virus antigen by agar gel precipitation test (AGPT) in the bursa of Fabricius (BF) after vaccination with an attenuated live vaccine. Eighty broilers (ROSS) were vaccination with an attenuated intermediary strain VGM-91 of infectious bursal disease virus (IBDV). Bursal samples of 5 randomly selected chickens were collected on vaccination day (day 0.) and on the 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, 10th, 12th, 14th, 16th, 18th, 23th and 28th day postvaccination (p.v.). The samples were tested by AGPT and they were histopathologically examined. Results achieved in this trial indicate that precipitating antigen, that emerges consequently to multiplication of the vaccinal strain virus in BF, can be detected in a period of 7 - 10 days p.v.. It means that precipitating IBDV antigens in BF of vaccinated broilers in this period, must not indicate infection with field strains, while later positive results points out to field infection with virus. During the trial, the VMG 91 strain of IBDV caused very mild to mild atrophy of the BF, limphopenia and lymphoid hyperplasia, mild hyperemia, hetrophil and macrophage accumulation of the interstitium |
