الفهرس 
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Abstract
flocks vaccinated against IBDThe results revealed that the IBD infection still a problem in the vaccinated flocksTwo forms of the disease still occur (clinical and subclinical forms) A major antigenic shift in IBD viruses has occurred in the field situation including classical , a typical classical , untypable variant and Del / E variant of IBDV (based on AC - ELISA) Revision of current vaccination programmes for control of both clinical and subclinical forms of the disease are requested.