Browsing by Author "Goldswain, Samantha"

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    Characterisation of lesions and associated immune cell populations in the lung of African buffalo (Syncerus cafe) infected with Mycobacterium Boris
    (Stellenbosch : Stellenbosch University, 2021-03) Goldswain, Samantha; Miller, Michele; Kleynhans, Leanie; Jennifer, Landolfi; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences: Molecular Biology and Human Genetics.
    ENGLISH ABSTRACT: A vast array of species is susceptible toMycobacterium bovis (M. bovis) infection, with varying pathogenesis and disease outcomes. Understanding the pathogenesis of disease is important for informing epidemiologic concerns and disease management strategies, especially in reservoir hosts, such as African buffaloes (Syncerus caffer). Therefore, this project is focused on characterisation of histologic morphology and associated immune cell populations in lung granulomas from M. bovis infected African buffalo to advance knowledge of disease development in buffaloes. A scoring system was developed to compare numbers and distributions of different immune cells, as well as other pathologic changes in bovine tuberculosis (bTB) pulmonary granulomas. In addition, an immunohistochemistry (IHC) staining technique was optimised for immune cell surface marker detection in buffalo lung tissues. Formalin-fixed and frozen tissues were available from M. bovis naturally infected buffaloes from Hluhluwe-iMfolozi Park, South Africa. Formalin-fixed lung tissues were selected based on gross lesion scores that represented a range of severity. Lung sections from 14 buffaloes were stained with haematoxylin and eosin (H&E) to assess the histologic morphology of granulomas. Microscopic characteristics were then scored based on six categories. In addition, immunohistochemical techniques were optimised using antibodies that detected immune cell surface antigens (CD3, CD4, CD21, CD163, NCR1). This study documented characteristics of a low histologic stage granuloma to include macrophages/multinucleated giant cells (MNGCs) at the core, lymphocytic infiltration surrounding the macrophages, and minimal to no necrosis and fibrosis. Granulomas compatible with more advanced disease were necrotic, with macrophages surrounding the necrotic core, lymphocytes located peripherally, and were encapsulated by a fibrous capsule. More developed granulomas were not always mineralised. Based on IHC, CD3+ T lymphocytes and CD163+ macrophages/MNGCs were present in all granulomas examined; B cells (CD21+) were only present in higher stage granulomas; and natural killer (NCR1+) cells were not abundant in any of granulomas. The CD4 antibody did not stain buffalo tissues and therefore, distribution of this subset of T lymphocytes could not be evaluated. Ziehl-Neelsen staining was performed to detect the presence of acid-fast bacilli, however, no bacilli were visible in the slides analysed. The appearance of the buffalo pulmonary granulomas did not completely fit with the stages described in cattle (Wangoo et al., 2005). Therefore, a scoring system for categorising granulomas, adapted for buffaloes, should be investigated to provide a species-specific description that would be beneficial for understanding bTB pathogenesis. In summary, findings showed that lymphocytes and macrophages/MNGCs appear to be the predominant immune cell types present and their distribution and relative numbers appear to change as pulmonary granulomas develop. Characteristics such as increased fibrous encapsulation and development of a necrotic core appear to be similar to granulomas in cattle. However, mineralisation may not be a consistent feature, suggesting some species-specific differences that should be further investigated. This study also demonstrated that immunohistochemistry is a practical method for further characterisation of local immune responses to M. bovisinfection in buffalo. Further research with a larger sample set will be informative for understanding local and associating systemic immune responses to bTB in buffaloes.
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    Review of diagnostic tests for detection of mycobacterium bovis infection in South African wildlife
    (Frontiers Media S.A, 2021-01) Bernitz, Netanya; Kerr, Tanya J.; Goosen, Wynand J.; Chileshe, Josephine; Higgitt, Roxanne L.; Roos, Eduard O.; Meiring, Christina; Gumbo, Rachiel; De Waal, Candice; Clarke, Charlene; Smith, Katrin; Goldswain, Samantha; Sylvester, Taschnica T.; Kleynhans, Léanie; Dippenaar, Anzaan; Buss, Peter E.; Cooper, David V.; Lyashchenko, Konstantin P.; Warren, Robin M.; Van Helden, Paul D.; Parsons, Sven D. C.; Miller, Michele A.
    Wildlife tuberculosis is a major economic and conservation concern globally. Bovine tuberculosis (bTB), caused byMycobacteriumbovis (M. bovis), is themost common form of wildlife tuberculosis. In South Africa, to date, M. bovis infection has been detected in 24 mammalian wildlife species. The identification of M. bovis infection in wildlife species is essential to limit the spread and to control the disease in these populations, sympatric wildlife species and neighboring livestock. The detection of M. bovis-infected individuals is challenging as only severely diseased animals show clinical disease manifestations and diagnostic tools to identify infection are limited. The emergence of novel reagents and technologies to identify M. bovis infection in wildlife species are instrumental in improving the diagnosis and control of bTB. This review provides an update on the diagnostic tools to detect M. bovis infection in South African wildlife but may be a useful guide for other wildlife species.