Lesion characterization of organs and isolation of Marek’s disease virus in chickens in different poultry farms of Bishoftu, central Ethiopia
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Date
2022
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Addis Abeba University
Abstract
A cross sectional study was conducted on clinically diseased chickens suspected of Marek’s disease (MD) virus infection on three intensive commercial poultry farms from January, 2022 to May, 2022 in Bishoftu town. Clinical and post-mortem examination was conducted on 70 chickens suspected of Marek’s disease virus (MDV) infection, virus isolation on chicken embryo fibroblast (CEF) and molecular detection of Marek’s disease virus using real-time PCR was conducted. In most of the examined chickens, classical signs of MD were observed while some did not show any clinical sign. Out of the 70 necropsied chicken, atrophy of the Bursa of Fabricius was observed in 44 (62.8%), ‘gray eye’ and skin nodules in 2 (2.85%), hepatomegaly in 38 (54.2%), splenomegaly in 16 (22.85%), ovary nodules in 2 (2.85%), kidney and lung nodules in 3 (4.28%), and heart nodules in 7 (10%) chickens. Peripheral nerve enlargement was not observed in any of the examined chickens. 65 feather follicles and 5 spleen samples were collected in viral transport media from the 70 clinically examined chickens under sterile condition. Molecular detection and confirmation of MDV was done using real-time PCR on the 70 samples and 53 (75.71%) of the feather follicle samples came out to be positive. Isolation of MDV was performed on CEF cell culture. Out of the 7 pooled samples, virus was isolated from 5 (72.42%). The isolates developed characteristic cytopathic effects of rounding of cells and plaques starting from the 5th day of 2nd and 3rd blind passage. Histopathological examination of 17 tissue samples of the sciatic nerves, liver, spleen, ovary, heart and lungs revealed heavy lymphocytic infiltration and multifocal lymphocytic
nodules and also lymphocytic depletion was observed in the spleen. This study has confirmed the circulation of MDV in the study area showing clinical signs, lesions and cellular changes. Therefore, further study on the gross and histopathological lesions, isolation and molecular characterization of MDV, targeting different breeds, age group, and geographical areas on backyard and commercial poultry farms in Ethiopia is recommended
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Keywords
cell culture, Marek’s disease, Marek’s disease virus, polymerase chain reaction, virus isolation., chicken, histopathology, lesion characterization