الفهرس 
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Abstract
Gumboro disease (GD) or infectious bursal disease (IBD) is one of the dangerous avian viral diseases which cause great economic losses affecting poultry industries.IBD had an immunosupressive effect in addition to the other signs as retartded growth,decreased food conversion rate and increased mortalities.
The present study was planned to prepare and evaluate specific inactivated IBDV vaccines (either by formalin or BEI) and compare them with the imported
one.
The experimental results obtained in this work revealed the following: 1-Successful) propagation of the three obtained local isolates of IBDV in embryonated chicken eggs.The named isolate G-3 was the selected one where it had the highest titre and showed the highest rate of specific IBD lesions.
2-The 3rd passage (of each isolate) in ECE was passaged 2 successive times in susceptible chickens confirming that G-3 is the best one where the inoculated chickens showed the characteristic clinical and post mortum findings of IBD.
3-The bursa/body weight ratio was higher in infected chickens than in non-infected control birds. 4-It was found that AGPT could be used for the detection and identification of 1131)\’ in the homogenates of infected bursa and chicken embryos.
5-Complete inactivation of IBDV was obtained after 24 and 44 hours after inactivation with formalin and Binary respectively.
6-Serum neutralization test showed that the IBDV neutralizing antibodies began to appear in vaccinated chickens from the second week post vaccination and reached
their peak by the fourth to the fifth week post vaccination then decline from the second month till the lowest titre at the 6th month,but these antibodies remain higher in chickens received booster dose and began to decrease by the third month.
7-The inactivated (local and imported ) IBDV vaccines did not affect the immune
response of vaccinated chickens against Newcastle disease vaccine i.e.,they have no immunosupressive effect.
8-The challenge of vaccinated birds did not affect their bursae and resulted in rising of their antibody titre.
9-The evaluation of cell-mediated immunity by use of lymphocyte transformation test showed an increase in the stimulation index from the third week post vaccination in all groups but this increase was observed from the second week post vaccination in groups received booster dose.
I0-Also,AGPT used successfully as a screening test to detect the presence of IBDV pricipitines in vaccinated chicken sera.
11-It was foun that the prepared inactivated (formalin and Binary ) IBDV vaccines could be used safely for vaccination of susceptible chickens up to 3 months with a protection percentage of 80 and after 6 months of storage at 4 degree with a
protection ratio of 60%.
12-The induced immunity in vaccinated chickens survived for at least 5 months post vaccination and declined to the lowest level by 6th month.At 6 months of ,age
resistance take place.
*It was concluded that inactivated IBDV vaccines (local&imported) are safe,immunogenic and have no immunosupressive ettecalowever,the formalized vaccine seemes to be better than the Binary where the duration of immunity some W hate longer than that obtained with binary with higer protection%.