Browsing by Author "Mohamed Najimudeen, Fathima Shahnas"
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- ItemOpen AccessPathogenesis of and, host responses to Canadian 4/91 infectious bronchitis virus infection in specific pathogen free chickens(2021-07-30) Mohamed Najimudeen, Fathima Shahnas; Abdul Careem, Mohamed Faizal; Cork, Susan; Van Marle, Giudo; van der Meer, Franciscus; Abdul Careem, Mohamed FaizalInfectious bronchitis (IB) is an economically important disease in chickens caused by infectious bronchitis virus (IBV), which is a coronavirus. The 4/91 strain of IBV is globally distributed with a broad tissue tropism. In Canada, the 4/91 IBV strain was first recorded in 2011 and was dominant until 2017 in Eastern Canadian poultry flocks. The affected flocks presented clinically with respiratory and egg production problems. Information is lacking on the pathogenesis of Canadian (CAN) 4/91 IBV and host responses to this virus in chickens. Thus, the objectives of the thesis research were to determine the impact of the CAN 4/91 IBV variant on egg production and quality and then, to investigate the nephropathogenicity and host responses mounted against this virus infection in specific pathogen-free (SPF) chickens. To investigate CAN 4/91 IBV infection in laying hens, 28-week-old hens were infected with CAN 4/91 IBV and compared with uninfected controls. The hens were monitored daily for egg production and quality and for other clinical signs. Oropharyngeal (OP) and cloacal (CL) swab samples were collected at predetermined time points. A subset of hens from each group were euthanized at 6 and 10 days post-infection (dpi). We observed that the CAN 4/91 IBV isolate has a very broad tissue tropism including the reproductive tract. However, it did not significantly affect egg production or egg quality with minor histological changes in the shell gland. The analysis of the kidneys showed histopathological lesions in infected animals and significant recruitment of T cells and macrophages. For investigation of pathogenicity of CAN 4/91 IBV in the respiratory tract and kidneys of young chickens, one-week-old, unsexed chickens were infected with CAN 4/91 IBV maintaining uninfected controls. The chickens were monitored daily for clinical signs. At 3, 7 and 10 dpi, 5 chickens from each group were euthanized. IBV replicated and induced histopathological lesions, upregulation of genes of proinflammatory mediators and significant recruitment of T cells and macrophages in lung and kidney tissues. Overall, our study contributed to the understanding of the pathogenesis of and host responses to CAN 4/91 IBV infection in SPF layer chickens.