الفهرس 
AbstractOnly 14 pages are availabe for public view
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Abstract
Since the initial description of IB in Egypt, the disease still occurs
in vaccinated and unvaccinated chicken farms. 25 isolates of IBV could
be isolated; of them at least four multiple serotypes (variants) were
identified. Variant strains in pathogenicity studies produced within 24 -
48 h. p.i., respiratory distress and nephritis - nephrosis associated with
20%-100% mortality. Cross protection study revealed poor
imrnunogenicity acquired by live IB-HI20 to combat challenge with
variant strains of lB. It could be proposed that revision of vaccination
regime and type of used vaccines should be implemented either as local
production or imported.