Infectious bronchitis virus (IBV) infection in chickens: Some aspects of pathogenesis and diagnosis
Date
2023-12-12
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Abstract
Infectious bronchitis virus (IBV) causes infectious bronchitis (IB) in chickens. IB has a significant impact on the poultry industry. Therefore, this thesis focuses on some aspects of pathogenesis and diagnosis of IBV in chickens. The quantitative polymerase chain reaction (qPCR) technique is used for the detection and quantification of IBV genome load. In this thesis, performance characteristics of the digital PCR (dPCR) technique were compared to qPCR assay for the detection and quantification of IBV genome loads. The dPCR assay had higher assay sensitivity and precision than qPCR assay. Hence, dPCR is a better technique to detect and quantify IBV genome load. In this thesis, we further aimed to evaluate the impact of the presence of maternal antibodies on IBV infection in primary and secondary lymphoid organs. The IBV genome load and histopathological lesion scores were significantly lower in progenies from vaccinated hens compared to progenies from non-vaccinated hens in oropharyngeal and cloacal swabs and in bursa of Fabricius (BF) and cecal tonsils (CT). These findings suggest that the presence of maternal antibody in progeny could provide some degree of protection against IBV infection in BF and CT. In this study we aimed to compare IBV pathogenesis and host immune responses in young male and female chickens. No significant difference was observed between the infected male and female chickens in the IBV shedding, IBV genome load in trachea, lung, kidney, BF, thymus, spleen, and CT and in the IBV-induced lesion in all the tissues. A significantly higher percentage of IBV immune-positive area was observed in the infected male chickens compared to female chickens in kidney. There was no significant difference between infected male and female chickens in all the tissues in the B lymphocytes percentage and in all tissues except trachea in the percentage of cluster of differentiation 8 positive (CD8+) T cells, where female chickens had a higher recruitment when compared to male chickens. Most of the findings of this study suggest that the sex of the chickens does not play a significant role in the pathogenesis of IBV and the host immune response in young chickens.
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Keywords
Infectious bronchitis virus (IBV), Quantitative polymerase chain reaction (qPCR) assay, Digital PCR (dPCR) assay, Maternal antibody, Lymphoid organs, Sex
Citation
Ishara Muhammadu Isham, F. (2023). Infectious bronchitis virus (IBV) infection in chickens: some aspects of pathogenesis and diagnosis (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.