الفهرس 
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Abstract
Infectious bursal disease virus remerged frequently in
Egypt, causing serious economic losses. The disease is acute
contagious disease in young chickens from 3-6 weeks of age. In
present study forty field bursa samples were collected from
different Egyptian governorates, detection of IBDV in the
collected samples were done using RT-PCR. Eight samples
showed positive results by percent of (20%). Sequence analysis
and characterization of the hyper variable region of VP2 gene
from four strains purified from the PCR product showed many
amino acid substitutions that may affect IBDV antigenicity and
virulence. Comparative phylogenetic analysis based on the
sequence of the hypervariable region of VP2 gene show that the
strains were closer to Giza 2008 strains. This study reports the
continuous circulation of vvIBDV strains in vaccinated flocks 4
governorates “Giza, Sharkia, Behira and Dakahlia”, in Egypt
during year 2015. There are need to review the control and
vaccination strategy of IBDV in broiler flocks specially the
extensive abuse of using classical vaccines.