الفهرس 
Review of literature
Bovine TuberculosisOnly 14 pages are availabe for public view
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Abstract
Bovine tuberculosis still represents a universal threat that creates a wider range of public and animal health impacts. The number of infected cattle with tuberculosis in Egypt is increasing annually, probably as a result of the importation of live animals from countries where bovine tuberculosis is predominant. Therefore, the current study was conducted to investigate the prevalence of tuberculosis in imported beef cattle. During the period from September 2020 to March 2022, 2150 slaughtered beef cattle were examined. Sixty animals (2.79%) of them showed tuberculous lesions grossly. Depending on the gross morphologic lesions, tuberculous cases were classified into generalized tuberculosis (9 cases, 15%) and localized tuberculosis (51, 85%). Localized cases were subdivided into pulmonary tuberculosis (28, 46.66%) and extra-pulmonary tuberculosis (23, 38.33%). Specimens were collected for histopathological examination, granuloma staging, and Ziehl-Neelsen (ZN) staining. Based on the histopathological examination, the granulomas were classified into: Stage I (158, 21.43%), Stage II (187, 25.37%), Stage III (156, 21.16%), and Stage IV (236, 32.02%). Forty-two out of 60 animals (70 %) yielded a positive result with the ZN technique, with 35 cases showing a paucibacillary form, whereas 7 cases showed a pluribacillary form. AFB was mainly demonstrated within macrophages, multinucleated giant cells (MNGCs) and the necrotic center of granulomas. 10 samples presented a positive result to ZN technique were subsequently subjected to real-time PCR analysis through DNA extraction directly from the paraffin blocks for detecting IS6110 of mycobacterium tuberculosis complex (MTC). All ten samples gave positive by means of real-time PCR targeting IS6110.
One of the most important steps in the pathogenesis of this disease and granuloma formation is the phagocytosis of tuberculous bacilli by macrophages. However, scarce information is available about the dynamics of the granuloma-stage immunological response. Therefore, immunohistochemistry was used in this work to evaluate the expression of MAC387, CD68, iNOS, HLA-DR, CD163 and Arg1 in different stages of TB granulomas. selected five samples were subjected to an immunohistochemical study of MAC387, CD68, iNOS, HLA-DR, CD163 and Arg1 expression by macrophages according to granuloma stages. Immunohistochemical analysis revealed that the immunolabeling of MAC387, CD68+, iNOS+, and HLA-DR+ macrophages significantly reduced as the stage of granuloma increased from stage I to stage IV (P <0.008, P<0.003, P<0.002, and P<0.002, respectively). However, the immunolabeling of Arg1+ and CD163+ macrophages significantly increased as the stage of granuloma increased from stage I to stage IV (P<0.01, and P<0.001, respectively).
The parallel increase in the expression of CD68, iNOS, and HLA-DR (M1 markers) in early-stage granulomas and increase in the expression of Arg1 and CD163 (M2 markers) in late-stage granulomas, indicate a shift in the immune response along the infection, from a more effective proinflammatory immune response (M1 polarization) in the early stage to a tolerogenic immune response (M2 polarization) in the late- stage of the infections which allows the persistence of the disease.