الفهرس 
HistopathologyOnly 14 pages are availabe for public view
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Abstract
Studies were carried out to investigate some aspects related to Epizootiology of severe outbreaks
of infectious bursal disease (IBD). Moreover, pathogenicity of recent IBD virus local isolate and
disease control by vaccination were studied.All invistigated outbreaks occurred at 26-40 days of
age, this farm were adapted with different classes of commercial stndard live IBD
vaccines.(”intermediate” and/or ”hot”) of standard serotype live IBD vaccines IBDV was confirmed
by detection of IBDV antigens by AGPT in bursal homogenates from acutely affected birds.
pathogenicity study of recent IBDV local field isolate no. 18 revealed that the mortality was
55% Laboratory experments were desigend to evaluate the control of vv IBDV infection by vaccination
with intermediate (D78, Bursimune ) or hot (228E) when vaccinate egg- type chickens which have
insignificant maternal antibodies levelsat 49- day- The results of the oculonasal challenge
with vvIBDV every 24 hours PV showed that there is early protection against mortality not against
bursal atrophy after 48hs PV in group vaccinated with hot (288E) and after 72hs PV in group
vaccinated with intermediate vaccine (D78 and Bursimune) and this early protection against
mortality may due to induction of interferon in the bursa of fabricious by life vaccine The results
of occlunasal chalenge with the same isolate at 7’ 14 ’!-nd 21 day PV with intermediate (D78,
Bursimune ) or hot (228E) showed that there compete protection against mortality not against bursal
atrophy after 7 day in group vaccinated with hot (228E) and after 14 day PV in group vaccinated
with intermediate vaccine (D78 and Bursimune)