الفهرس 
AbstractOnly 14 pages are availabe for public view
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Abstract
This study was performed to evaluate IHC as a tool in diagnosis of IBV infection in chicken in comparison with RRT-PCR. Also to declare the pathogenesis of challenged IBV genotype 6/82 and live infectious bronchitis H120 vaccine in chicken. The experiment was carried out on 140 one day old broiler saso chicks. They were divided into four isolated groups, 35 birds each. Group (A) kept as a control group not vaccinated or infected, group (B) not vaccinated but inoculated with IBV, group (C) was vaccinated once with infectious bronchitis H120 vaccine at one day old and was challenged at 28 day old while group (D) was vaccinated twice with infectious bronchitis H120 vaccine at one day then at 14 day old and was challenged at 28 day old. Tissue specimens were collected from the nasal chonchae, trachea, lungs, liver, heart, kidney, brain, Bursa of Fabricious, thymus, spleen, cecal tonsils, gizzard and proventriculus at 1st , 3rd , 7th , 14th , 17th , 28th , 31st , 35th and 40th days old for histopathology, and IHC. Specimens from trachea and kidneys were subjected to RRT-PCR and IHC for IBV detection. IBV antigen was detected by IHC but not by RRT-PCR in trachea of vaccinated chicken at 14 day old and trachea of chicken in group D at 12 day PC. Also IBV antigen was detected by IHC and not by RRT-PCR in kidneys at 3, 14 days old in chicks vaccinated once, at 17 day old in chicks vaccinated twice and in group C at 12 day PC. The histopathological lesions were more severe in case of infection than in vaccination. Also histopathological lesions were more severe in group B which not vaccinated and persist longer time than groups C and D. The main pathological lesions recorded in the trachea of infected groups with IBV were deciliation, necrosis in respiratory epithelium followed by regeneration with hyperplasia of lining epithelium and goblet cells. Also kidney lesions were necrosis in the epithelium lining tubules with vacuolation. Liver histopathology reveled necrosis in hepatocytes in addition lymphoid organs showed depletion. IBV antigen was detected in all examined organs in addition inside erythrocytes and endothelial lining of blood vessels. This is the first time to detect IBV in gizzard and brain of infected chicken. IHC is highly sensitive in diagnosis of IBV than PCR. IHC is cheaper and useful for detection the pathogenicity and distribution of IBV in different organs and tissues.