الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
This study successfully characterized seven vvIBDV and one classical strain from field cases of IBD in Egypt during the period from 2014 to 2015. The genotyping of Egyptian vvIBDV indicated progressive evolution of IBDV in Egypt and they were closely related to previous isolated strains in Egypt. This study indicated continuous evolution of the vvIBDV in the Egyptian environment. The presence of one virus of classic attenuated strain in the examined isolates revealed circulation of vaccine viruses in the field and that might be due to improper vaccine application in the field that permitted emergence antigenic variant strain circulation which may attribute to sever post vaccination reaction of intermediate-plus vaccines. The intensive use of vaccination programs performed with live attenuated viruses might lead to the possibility of emergence of mutants and subsequently they constantly changed their pathogenic potential and that require review the vaccination programs in Egypt.