الفهرس 
1- IntroductionOnly 14 pages are availabe for public view
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Abstract
The epizootiological investigation of 24 current infectious bursal diseaseIBD) outbreaks among vaccinated chickens flocks during 2009-2011 at 24-40 days of age these outbreaks were characterized by typical clinical signs and
hemorrhagic gross lesions. Moreover, the mortality rates in these flocks ranged
between 3-9% (average 5.47 %) in commercial broilers farms, 3.4-11% (average
6.73 %) in commercial layer replacement pullets and 5.5-10% (average 7.85%) in
native balladi varieties. Management and hygienic condition were sub-optimal in
all investigated farms. Vaccination in these farms was adapted with different
classes of standard live vaccines.
IBDV was confirmed by detection of IBDV antigens by AGPT in bursal
homogenates from acutely affected birds. Detection of IBDV RNA in bursal
homogenates by amplification of 248bp of VP2 gene by RT-PCR confirms the
existence and circulation of IBD in the field. The result of pathogenicity study of
recent IBDV local field isolate No. (13), at 49 days old white egg-type male
chickens revealed that the mortality rate was 20%.
Laboratory experiment was designed to evaluate the control of vvIBDV
infection by vaccination with live intermediate (Moulthroup; S706 and Lukert
7/92) and intermediate plus (G603; IBD2512 and Bursine plus) IBDV vaccines.
The results of the protection against challenge with the vvIBDV isolate, after
vaccination at 49-day-old with live intermediate and intermediate plus IBDV
vaccines in white egg-type male chickens and challenge with vvIBDV isolate No.
(13) 7-days and 14-days PV., showed that there was complete vaccinal protection
against mortality, except groups which vaccinated with intermediate (S706 and
Lukert 7/92) IBDV vaccines and challenged at 56 day old, which gave partial
protection against mortality, whereas the mortality was 10% in each group,
comparison with mortality in non vaccinated challenged groups 30% and 40%
after 7 days of infection at 56 and 63 day-old, respectively. This protection
against mortality but, not against bursal atrophy, or histological changes.
On serological response to live NDV and oil emulsion inactivated AI
vaccines revealed that the challenge virus and used IBDV vaccines causing
immunosuppression to the response to live NDV and oil emulsion inactivate AI
vaccines.