Johne�s disease in ruminants is caused by the pathogenic bacterium Mycobacterium avium subspecies paratuberculosis. An experimental infection model in sheep was developed as a prelude to the testing of new vaccines and the development of improved diagnostic assays for Johne�s disease. The final challenge model developed used four doses of 10⁹ viable organisms given at two to three day intervals. Gross and microscopic lesions were found in a high proportion of sheep (80%) at ten months post challenge. There was considerable variation in immune responses from animals challenged with different strains of M. paratuberculosis. Sheep challenged with a low passage laboratory culture of strain (W) M. paratuberculosis, produced strong lymphocyte transformation responses and Interferon gamma (IFN-γ) production at two months post challenge. Subsequent necropsy and culture from intestinal tissues showed only a low level of infection (25%). In comparison a primary tissue isolate of M. paratuberculosis (JD3) resulted in higher (60-90%) infection rates in orally challenged animals. The immune profile from these animals showed very little reactivity for the first three months post challenge, after which IFN-γ production could be detected. Antibody production and lymphocyte transformation response could not be measured until at least seven months post challenge. Sheep challenged with the primary tissue isolate instilled directly into the tonsil resulted in equivalent levels of Johne�s disease to those obtained with oral challenge. However, intratonsillar challenge resulted in higher levels of immune reactivity than oral challenge. The proprietary Johne�s vaccines; NeoparsecTM and GudairTM and an Aqueous vaccine were tested in sheep. The immunological reactions of the sheep to these vaccines showed some variations between the two separate studies, with the NeoparasecTM and GudairTM vaccines evoking high levels of CMI and humoral reactivity within two months of vaccination. Detailed immunological examination of gut associated lymphoid tissues were carried out on subgroups of animals that were either vaccinated or non-vaccinated and went on to develop disease or were immune to experimental challenge. The results showed that the diseased animals examined had multibacillary lesions and strong CMI and humoral responses. There were decreased proportions of CD4⁺, CD8⁺ and CD25⁺ T cells in peripheral blood and gut associated lymphatics of diseased animals compared with the immune or unchallenged subgroups. Profiles from the immune subgroups showed a stronger lymphocyte transformation response than case matched diseased animals. Tissues from immune animals showed increased proportions of B cells above those seen in diseased or unchallenged animals. This study has resulted in the development of a robust experimental sheep model in which Johne�s disease occurs in a high proportion of challenged animals. Critical time points for the establishment of infection or disease have been determined. It can be used in the future to evaluate protective efficacy of vaccines or to critically chart immunological profiles that are associated with infection, disease or protective immunity. Considerable research is needed to develop improved diagnostic tests to identify patterns of immunity during the early stages of infection or while the animal has subclinical disease.

Johne�s disease in ruminants is caused by the pathogenic bacterium Mycobacterium avium subspecies paratuberculosis. An experimental infection model in sheep was developed as a prelude to the testing of new vaccines and the development of improved diagnostic assays for Johne�s disease. The final challenge model developed used four doses of 10⁹ viable organisms given at two to three day intervals. Gross and microscopic lesions were found in a high proportion of sheep (80%) at ten months post challenge. There was considerable variation in immune responses from animals challenged with different strains of M. paratuberculosis. Sheep challenged with a low passage laboratory culture of strain (W) M. paratuberculosis, produced strong lymphocyte transformation responses and Interferon gamma (IFN-γ) production at two months post challenge. Subsequent necropsy and culture from intestinal tissues showed only a low level of infection (25%). In comparison a primary tissue isolate of M. paratuberculosis (JD3) resulted in higher (60-90%) infection rates in orally challenged animals. The immune profile from these animals showed very little reactivity for the first three months post challenge, after which IFN-γ production could be detected. Antibody production and lymphocyte transformation response could not be measured until at least seven months post challenge. Sheep challenged with the primary tissue isolate instilled directly into the tonsil resulted in equivalent levels of Johne�s disease to those obtained with oral challenge. However, intratonsillar challenge resulted in higher levels of immune reactivity than oral challenge. The proprietary Johne�s vaccines; NeoparsecTM and GudairTM and an Aqueous vaccine were tested in sheep. The immunological reactions of the sheep to these vaccines showed some variations between the two separate studies, with the NeoparasecTM and GudairTM vaccines evoking high levels of CMI and humoral reactivity within two months of vaccination. Detailed immunological examination of gut associated lymphoid tissues were carried out on subgroups of animals that were either vaccinated or non-vaccinated and went on to develop disease or were immune to experimental challenge. The results showed that the diseased animals examined had multibacillary lesions and strong CMI and humoral responses. There were decreased proportions of CD4⁺, CD8⁺ and CD25⁺ T cells in peripheral blood and gut associated lymphatics of diseased animals compared with the immune or unchallenged subgroups. Profiles from the immune subgroups showed a stronger lymphocyte transformation response than case matched diseased animals. Tissues from immune animals showed increased proportions of B cells above those seen in diseased or unchallenged animals. This study has resulted in the development of a robust experimental sheep model in which Johne�s disease occurs in a high proportion of challenged animals. Critical time points for the establishment of infection or disease have been determined. It can be used in the future to evaluate protective efficacy of vaccines or to critically chart immunological profiles that are associated with infection, disease or protective immunity. Considerable research is needed to develop improved diagnostic tests to identify patterns of immunity during the early stages of infection or while the animal has subclinical disease.

Mycobacterium tuberculosis (M. tuberculosis) , the etiological agent of tuberculosis, is an intracellular bacterium which persists within macrophages. Successful control of tuberculosis depends on T-cell-mediated immunity. Immune protection involves the development of a Th1 response characterised by the secretion of cytokines such as IL-12, IFN-γ and TNF-α. The progression towards disease in humans and mice is often associated with a Th2 response characterised by the secretion of cytokines such as I L-4 and I L-10. Mycolic acids, the major cell wall lipid of M. tuberculosis, were previously shown to have a marginally protective effect on the development of disease in Balb/c mice when administered intravenously at an optimal dose of 25 µg one week before intravenous M. tuberculosis infection. Here it is shown that the protective effect is highly significant when infection is done intranasally. The protective effect of 25 µg mycolic acids against tuberculosis could not be explained by induction of a longer lasting Th1 response in Balb/c mice. This was determined by using semi-quantitative RT-PCR on the mRNA of cytokines characteristic of the different immune responses. It was observed that maximum sensitivity was obtained at the lowest possible PCR cycle and template concentrations for the samples. Mycolic acids were the first non-protein antigens shown to induce an immune response after presentation on CD1 membrane proteins. Balb/c mice predominantly generate a Th1 response during the first 3 - 4 weeks of M. tuberculosis infection, whereas they generate a Th2 response in the following weeks. Even though the protective effect of 25 µg mycolic acids could not be associated with a prolonged Th1 immune response in infected mice, it did induce IL-12 and IL-10 mRNA in uninfected mice. These cytokines are primarily. / Dissertation (MSc (Biochemistry))--University of Pretoria, 2005. / Biochemistry / unrestricted

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Bovine tuberculosis (BTB) is a chronic, infectious disease found in domestic livestock and wildlife, and has serious biodiversity, economic and public health implications. African buffalo act as a wildlife reservoir of BTB, maintaining and transmitting the disease within the environment. The research presented in this thesis addresses the role of host genetic variation in resistance to BTB infection in African buffalo, and reviews the possible practical application of such information. Annual BTB prevalence within the African buffalo population in Hluhluwe iMfolozi Park, South Africa, was evaluated over a seven year period in order to define the extent of M. bovis infection. Prevalence changes over time suggest that the test and cull operation currently in place is performing successfully with respect to the original aims of the programme. A review of genetic studies of BTB in livestock and wildlife collated previous findings in this field and provided a collection of possible candidate genes and variants. It also highlighted a lack of research in wildlife, and the limitations of working with species with insufficient genetic data. To overcome the absence of whole-genome data, next-generation sequencing was performed on nine African buffalo, in order to identify novel genetic variants in this species. Upwards of 76 000 novel SNPs within gene regions were identified, and subsequent fluorescent genotyping of 173 SNPs showed a 57% validation rate. From the validated set, 69 SNPs located in genes related to the immune system were selected for association testing with BTB status in African buffalo, and were fluorescently genotyped in 868 individuals. Three SNPs, in the Solute Carrier family 7, member A13 (SLC7A13), Deleted in Malignant Brain Tumour-1 (DMBT1) and Interleukin 1 alpha (IL1α) genes, were identified as significantly associated with BTB status. Very little sequence information of the NRAMP1 (SLC11A1) gene was obtained from the next-generation sequencing performed, and this gene has been associated with brucellosis, salmonella and paratuberculosis in other animal species, making it an excellent candidate for BTB resistance. To characterise this gene in African buffalo, Sanger sequencing was performed to generate the complete coding region, and partially sequence the 5’UTR, intronic and 3’UTR regions. Fifteen novel polymorphisms and three microsatellites were identified within the gene. Finally, a review was prepared to assess the applicability of genetic information on BTB resistance to selective breeding programmes for African buffalo. Phenotypic, marker-assisted and genomic breeding strategies were discussed, with particular emphasis on their suitability to African buffalo. Identifying genes and variants involved in BTB resistance in African buffalo provides potential targets for drug or vaccine development, as well as information that could be incorporated into selective breeding programmes. This may support new management options for controlling the BTB epidemic in the game parks of South Africa, as an alternative to, or in conjunction with, lethal control / AFRIKAANSE OPSOMMING: Beestuberkulose (BTB) is ‘n chroniese, aansteeklike siekte wat in vee en wild voorkom en wat ernstige gevolge vir die ekonomie, biodiversiteit en openbare gesondheid inhou. Die Kaap-buffel is ‘n wild reservoir vir BTB wat die siekte onderhou en versprei in die omgewing. Die navorsing wat in hierdie tesis aangebied word fokus op die rol van gasheer genetiese variasie in die weerstand teen BTB infeksie in Kaap-buffels en gee ‘n oorsig van die moontlike praktiese toepassing van die resultate. Die jaarlikse BTB voorkomsyfer in die Kaap-buffel bevolking in die Hluhluwe iMfolozi Park in Suid-Afrika is oor ‘n tydperk van sewe jaar geëvalueer om die omvang van M. bovis infeksie te bepaal. Die verandering in voorkomsyfer oor tyd dui daarop dat die toets-en-slag operasie wat tans gebruik word die oorspronklike doelwitte van die program suksesvol bereik. ‘n Oorsig en vergelyking van vorige genetiese studies van BTB in vee en wild het ‘n versameling van moontlike kandidaatgene en –variante verskaf. Dit het ook die gebrek aan navorsing in wildediere uitgewys en die navorsingsbeperkinge wanneer ‘n spesie met onvoldoende genetiese data bestudeer word benadruk. Aangesien daar nie heel genoom data beskikbaar is nie, is volgende-generasie volgordebepaling van 9 Kaap-buffels gedoen om nuwe genetiese variasies in hierdie spesie te identifiseer. Meer as 76 000 nuwe enkel-nukleotied polimorfismes (ENPs) binne geen-areas is geïdentifiseer en die daaropvolgende genotipering van 173 ENPs het ‘n bevestigingskoers van 57% gehad. Vanuit die bevestigde stel ENPs is 69 gekies vir assosiasietoetse met BTB status in die Kaap-buffel en genotipering van 868 individue is gedoen. Drie ENPs, in die Solute Carrier family 7, member A13 (SLC7A13), Deleted in Malignant Brain Tumour-1 (DMBT1) en Interleukin 1 alpha (IL1α) gene, was beduidend geassosieer met BTB status. Baie min volgorde inligting van die NRAMP1 (SLC11A1) geen is verkry uit die volgende-generasie volgordebepaling. Aangesien hierdie geen voorheen met brucellose, salmonella en paratuberkulose in ander dierespesies geassosieer is, is dit ‘n uitstekende kandidaat vir BTB weerstand. Hierdie geen is in Kaap-buffels gekarakteriseer deur Sanger volgordebepaling van die volledige koderende, gedeeltelike 5’UTR, introniese en 3’UTR areas te doen. Vyftien nuwe polimorfismes en drie mikrosatelliete is geïdentifiseer. Ten slotte is ‘n oorsigstudie gedoen om die toepaslikheid van BTB genetiese weerstandsdata in selektiewe telingsprogramme van Kaap-buffels te evalueer. Fenotipiese, merkerbemiddelde en genomiese teling strategieë is bespreek, met spesifieke klem op die geskiktheid van die metodes vir Kaap-buffels. Identifisering van gene en variante wat betrokke is by BTB weerstand in die Kaap-buffel bied potensiële teikens vir medikasie of entstof ontwikkeling, sowel as inligting wat in selektiewe telingsprogramme gebruik kan word. Dit kan nuwe bestuursopsies vir die beheer van die BTB-epidemie in die parke van Suid-Afrika bied as 'n alternatief vir, of in samewerking met, dodelike beheermetodes.

Orientador: Karina Paes Bürger / Coorientador: Lara Borges Keid / Banca: Samir Issa Samara / Banca: Raphaella Barbosa Meirelles Bartoli / Resumo: A tuberculose é uma doença infectocontagiosa de caráter zoonótico de grande importância em saúde pública, sendo seu diagnóstico e o conhecimento de sua epidemiologia, peças fundamentais na sua prevenção e controle. Este trabalho objetivou a comparação entre métodos diagnósticos para tuberculose bovina. Foram realizados diagnósticos pelo cultivo microbiológico, caracterização histopatológica e identificação de bacilos álcool-ácido resistentes (BAAR) e identificação molecular da infecção por Mycobacterium bovis em bovinos adultos abatidos em matadourosfrigoríficos sob Serviço de Inspeção Federal (SIF) no Estado de São Paulo e posteriormente, os municípios de origem destes animais foram geoprocessados. Durante o abate, foram identificadas e coletadas amostras de linfonodos com lesões macroscópicas sugestivas de tuberculose. O diagnóstico pelo cultivo microbiológico foi realizado em meio de cultura sólido, a caracterização histopatológica pela coloração com hematoxilina eosina (HE), a identificação de BAAR pela coloração de Ziehl-Neelsen (ZN) e o diagnóstico pela identificação molecular foi realizado a partir de DNA extraído das lesões sugestivas de tuberculose pela reação em cadeia pela polimerase (PCR, nested PCR e multiplex PCR) e a partir de DNA extraído das colônias isoladas para identificação do M. bovis utilizando-se a PCR e a multiplex PCR. Dentre as lesões sugestivas de tuberculose observadas, 50% (25/50) foram identificadas em linfonodos retrofaríngeos e todas foram caracterizadas como caseosas. Houve crescimento de colônias características de M. bovis em 56% (28/50) das amostras, 64% (32/50) das amostras foram consideradas positivas pela coloração com HE e 52% (26/50) pela coloração confirmatória de ZN (identificação de BAAR). A PCR a partir de DNA extraído das lesões teciduais apresentou 38% (19/50) das amostras positivas e a PCR a partir de DNA extraído das... / Abstract: Tuberculosis is a contagious infectious zoonotic disease of high importance in public health, which diagnosis and the epidemiology knowledge are essentials in this disease prevention and control. This study aimed to compare the different diagnostic tests for bovine tuberculosis. Microbiological culture, histopathological and molecular M. bovis diagnosis were made in adults bovines slaughtered in slaughterhouses under Inspection Federal Service - SIF in São Paulo State and after, the animals origin municipalities were geoprocessing. Samples of lymph nodes with macroscopic lesions suggestive of tuberculosis were identified and collected during the animals' slaughter. The microbiological diagnosis was made by culture in solid medium, histopathological characterization by staining with hematoxylin eosin (HE), identification of AFB by Ziehl-Neelsen (ZN) and the diagnosis by molecular identification was carried out from DNA extracted from the lesions suggestive of tuberculosis by polymerase chain reaction (PCR, nested PCR and multiplex PCR) and the DNA extracted from the colonies was isolated for M. bovis identification using PCR and multiplex PCR. Most injuries (50% - 25/50) was identified in retropharingeal and all of them were characterized as caseous. M. bovis colonies growth was characteristics in 56% (28/50) of the samples and64% (32/50) of the samples were positive by HE staining and 52% (26/50) for confirmatory ZN staining. The PCR directly from tissue showed 38% (19/50) of positive samples and the PCR from the colonies showed 56% (28/50) of positive samples. The kappa test (95%) between the diagnoses showed higher agreement between the molecular diagnostics of the colonies, followed by histopathological and molecular analysis of tuberculosis suggestive lesions toward the microbiological diagnosis. The highest sensitivity and specificity values were observed in the colonies molecular testing, followed by histopathological and ... / Mestre

Made available in DSpace on 2015-10-06T13:03:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-07-01. Added 1 bitstream(s) on 2015-10-06T13:18:27Z : No. of bitstreams: 1 000848328.pdf: 656185 bytes, checksum: ba38e54af54213676e5d46fe3f460e40 (MD5) / A tuberculose é uma doença infectocontagiosa de caráter zoonótico de grande importância em saúde pública, sendo seu diagnóstico e o conhecimento de sua epidemiologia, peças fundamentais na sua prevenção e controle. Este trabalho objetivou a comparação entre métodos diagnósticos para tuberculose bovina. Foram realizados diagnósticos pelo cultivo microbiológico, caracterização histopatológica e identificação de bacilos álcool-ácido resistentes (BAAR) e identificação molecular da infecção por Mycobacterium bovis em bovinos adultos abatidos em matadourosfrigoríficos sob Serviço de Inspeção Federal (SIF) no Estado de São Paulo e posteriormente, os municípios de origem destes animais foram geoprocessados. Durante o abate, foram identificadas e coletadas amostras de linfonodos com lesões macroscópicas sugestivas de tuberculose. O diagnóstico pelo cultivo microbiológico foi realizado em meio de cultura sólido, a caracterização histopatológica pela coloração com hematoxilina eosina (HE), a identificação de BAAR pela coloração de Ziehl-Neelsen (ZN) e o diagnóstico pela identificação molecular foi realizado a partir de DNA extraído das lesões sugestivas de tuberculose pela reação em cadeia pela polimerase (PCR, nested PCR e multiplex PCR) e a partir de DNA extraído das colônias isoladas para identificação do M. bovis utilizando-se a PCR e a multiplex PCR. Dentre as lesões sugestivas de tuberculose observadas, 50% (25/50) foram identificadas em linfonodos retrofaríngeos e todas foram caracterizadas como caseosas. Houve crescimento de colônias características de M. bovis em 56% (28/50) das amostras, 64% (32/50) das amostras foram consideradas positivas pela coloração com HE e 52% (26/50) pela coloração confirmatória de ZN (identificação de BAAR). A PCR a partir de DNA extraído das lesões teciduais apresentou 38% (19/50) das amostras positivas e a PCR a partir de DNA extraído das... / Tuberculosis is a contagious infectious zoonotic disease of high importance in public health, which diagnosis and the epidemiology knowledge are essentials in this disease prevention and control. This study aimed to compare the different diagnostic tests for bovine tuberculosis. Microbiological culture, histopathological and molecular M. bovis diagnosis were made in adults bovines slaughtered in slaughterhouses under Inspection Federal Service - SIF in São Paulo State and after, the animals origin municipalities were geoprocessing. Samples of lymph nodes with macroscopic lesions suggestive of tuberculosis were identified and collected during the animals' slaughter. The microbiological diagnosis was made by culture in solid medium, histopathological characterization by staining with hematoxylin eosin (HE), identification of AFB by Ziehl-Neelsen (ZN) and the diagnosis by molecular identification was carried out from DNA extracted from the lesions suggestive of tuberculosis by polymerase chain reaction (PCR, nested PCR and multiplex PCR) and the DNA extracted from the colonies was isolated for M. bovis identification using PCR and multiplex PCR. Most injuries (50% - 25/50) was identified in retropharingeal and all of them were characterized as caseous. M. bovis colonies growth was characteristics in 56% (28/50) of the samples and64% (32/50) of the samples were positive by HE staining and 52% (26/50) for confirmatory ZN staining. The PCR directly from tissue showed 38% (19/50) of positive samples and the PCR from the colonies showed 56% (28/50) of positive samples. The kappa test (95%) between the diagnoses showed higher agreement between the molecular diagnostics of the colonies, followed by histopathological and molecular analysis of tuberculosis suggestive lesions toward the microbiological diagnosis. The highest sensitivity and specificity values were observed in the colonies molecular testing, followed by histopathological and ...

Orientador: Luis Antonio Mathias / Banca: Anna Monteiro Correia Lima / Banca: Adolorata Aparecida Bianco Carvalho / Banca: Raphaella Barbosa Meirelles Bartoli / Banca: Samir Issa Samara / Resumo: A tuberculose causada pelo Mycobacterium bovis é uma importante doença dos bovinos e constitui um grande problema de saúde animal, podendo também atingir humanos. Para o diagnóstico da infecção, e para desencadear as medidas sanitárias decorrentes desse diagnóstico, o Programa Nacional de Controle e Erradicação de Brucelose e Tuberculose (PNCEBT) estabelece a utilização de testes intradérmicos de tuberculinização. O objetivo deste estudo foi avaliar as respostas à tuberculina (PPD) aviária e à tuberculina bovina apresentadas por animais sensibilizados com inóculos inativados de M. bovis e de M. avium, e comparar os resultados do teste da prega caudal (TPC), do teste cervical simples (TCS) e do teste cervical comparativo (TCC) para diagnóstico da tuberculose bovina nos animais sensibilizados e em animais não sensibilizados. Os resultados mostraram que: a repetição dos testes não influiu na proporção de resultados positivos; houve animais sensibilizados com M. bovis que apresentaram reação até 500 dias após a sensibilização; em animais sensibilizados com M. avium, a especificidade do TCC foi superior à do TCS e à do TPC, e o TCC mostrou-se efetivo para discriminar reações induzidas pelo inóculo desse microrganismo; em animais sensibilizados com M. bovis, o TCC apresentou menor sensibilidade do que os outros dois testes; o ponto de corte do TCS e do TCC com melhor combinação de sensibilidade e especificidade foi inferior ao ponto adotado pelo PNCEBT para diagnóstico em animais n... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Tuberculosis caused by Mycobacterium bovis is an important disease in cattle e a great problem for animal health that can reach humans. For the diagnosis of the infection and the consequent sanitary measures, the National Program for Control and Eradication of Brucellosis and Tuberculosis (PNCEBT) establish the use of intradermal tuberculin tests. The aim of this study was to analyze the response to the avian and bovine tuberculin (PPD) developed by cattle sensitized with inactivated inoculum of M. avium and M. bovis. Another aim was to compare the results of the caudal fold test (CFT), the comparative cervical test (CCT), and the simple cervical test (SCT) for tuberculosis diagnosis in the sensitize animals and in animals that have not been sensitized. Repetition of the tests did not influence the proportion of positive results. There were animals sensitized with M. bovis showing reaction up to more than 500 days post sensitization. In animals sensitized with M. avium, the specificity of the CCT was higher than that of CFT and SCT, and CCT was able to discriminate the unspecific reaction induced by M. avium inoculum. In animals sensitized with M. bovis, CCT had lower sensitivity than the other two tests. The SCT and CCT cut-off with the best combination of sensitivity and specificity was lower than that adopted by the PNCEBT for the tuberculosis diagnosis in naturally infected animals. SCT hat good agreement with the other two tests, but the agreement between CFT and CCT was... (Complete abstract click electronic access below) / Doutor

Please read the abstract in the 00front part of this document / Dissertation (MSc Agric (Production Physiology))--University of Pretoria, 2006. / Animal and Wildlife Sciences / unrestricted

Thesis (PhD (Molecular Biology and Human Genetics))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The growing global epidemic of human tuberculosis (TB) results in 8 million new cases of this disease and 2 million deaths annually. Control thereof will require greater insight into the biology of the causative organism, Mycobacterium tuberculosis, and into the pathogenesis of the disease. This will benefit the design of new vaccines and diagnostic assays which may reduce the degree of both disease transmission and progression. Animal models have played a vital role in the understanding of the aetiology, pathogenesis, and treatment of TB. Much of such insight has been obtained from experimental infection models, and the development of new vaccines, for example, is dependant on these. Nonetheless, studies utilising naturally occurring TB in animals, such as those which have investigated the use of interferon-gamma release assays (IGRA) for its diagnosis, have contributed substantially to the body of knowledge in this field. However, there are few such examples, and this study sought to identify and investigate naturally occuring animal TB in South Africa as an opportunity to gain further insight into this disease. During the course of this study, the dassie bacillus, a distinctly less virulent variant of M. tuberculosis, was isolated from a rock hyrax from the Western Cape Province of South Africa. This has provided new insight into the widespread occurrence of this organism in rock hyrax populations, and has given impetus to further exploring the nature of the difference in virulence between these pathogens. Also investigated was M. tuberculosis infection in dogs in contact with human TB patients. In so doing, the first reported case of canine TB in South Africa was described, v a novel canine IGRA was developed, and a high level of M. tuberculosis infection in these animals was identified. This supports human data reflecting high levels of transmission of this pathogen during the course of human disease. Additionally, the fact that infected companion animals may progress to disease and potentially act as a source of human infection was highlighted. However, an attempt to adapt a flow cytometric assay to study cell-mediated immune responses during canine TB revealed the limitations of such studies in species in which the immune system remains poorly characterised. The use of IGRAs to diagnose TB was further explored by adapting a human assay, the QuantiFERON-TB Gold (In-Tube Method), for use in non-human primates. These studies have shown that such an adaption allows for the sensitive detection of TB in baboons (Papio ursinus) and rhesus macaques (Macaca mulatta) and may be suitable for adaption for use in other species. However, they have also evidenced the limitation of this assay to specifically detect infection by M. tuberculosis. Finally, to contextualise the occurrence of the mycobacterial infections described above, and other similar examples, these have been reviewed as an opinion piece. Together, these investigations confirm that animal models will continue to make important contributions to the study of TB. More specifically, they highlight the opportunities that naturally occuring animal TB provides for the discovery of novel insights into this disease. / AFRIKAANSE OPSOMMING: Wêreldwye tuberkulose (TB) epidemie veroorsaak agt miljoen nuwe gevalle en twee miljoen sterftes jaarliks. Ingryping by die beheer hiervan vereis begrip van die biologie van die mikroörganisme Mycobacterium tuberculosis, die oorsaak van TB, asook van die patogenese van die siekte self. Hierdie kennis kan lei tot ontwerp van nuwe entstowwe en diagnostiese toetse wat gevolglik beide die oordrag- en vordering van die siekte mag bekamp. Dieremodelle speel lankal 'n rol in ons begrip van die etiologie-, patogenese- en behandeling van TB. Insig is grotendeels verkry vanaf eksperimentele infeksiemodelle, en ontwikkeling van entstowwe, onder andere, is afhanklik van soortgelyke modelle. Desnieteenstaande, studies wat natuurlike TB voorkoms in diere ondersoek, byvoorbeeld dié wat op die ontwikkeling van interferon-gamma vrystellingstoetse (IGVT) fokus, het merkwaardige bydrae gemaak tot kennis en begrip in hierdie studieveld. Daar is slegs enkele soortgelyke voorbeelde. Om hierdie rede is die huidige studie uitgevoer waarbinne natuulike diere-TB geïdentifiseer en ondersoek is in Suid-Afrika om verdere kennis en insig te win aangaande TB. Die "dassie bacillus", bekend om beduidend minder virulent te wees as M. tuberculosis, is tydens hierdie studie geïsoleer vanuit 'n klipdassie (Procavia capensis) in die Wes-Kaapse provinsie, Suid-Afrika. Insig in die wydverspreide voorkoms van hierdie organisme in klipdassie bevolkings is gevolglik verkry en verskaf momentum om die aard van verskil in virulensie tussen dié patogene te bestudeer. vii Voorts is M. tuberculosis infeksie bestudeer in honde wat in kontak is met menslike TB pasiënte en word die eerste geval van honde TB dus in Suid-Afrika beskryf. In hierdie groep diere, is 'n hoë vlak van M. tuberculosis infeksie geïdentifiseer deur gebruik te maak van 'n nuut ontwikkelde IGVT vir die diagnose van honde TB. Gevolglik ondersteun dié studie bevindinge van menslike studies wat toon dat besondere hoë vlakke van M. tuberculosis oordrag voorkom gedurende die verloop van die siekte. Verder toon die studie dat geïnfekteerde troeteldiere 'n bron van menslike infeksie kan wees. 'n Poging om 'n vloeisitometriese toets te ontwikkel om die aard van selgefundeerde immuunreaksies te bestudeer in honde met TB toon die beperkings van dergelike studies in spesies waarin die immuunsisteem gebrekkig gekarakteriseer is. Die gebruik van IGVT'e in die diagnose van TB is verder ondersoek deur 'n menslike toets (QuantiFERON-TB Gold, In-Tube Method) aan te pas vir die gebruik van nie-menslike primaat gevalle. Hierdie studies toon gevolglik dat so 'n aanpassing toepaslik is vir hoogs sensitiewe deteksie van TB in chacma bobbejane (Papio ursinus) en rhesus ape (Macaca mulatta), en mag ook aangepas word vir gebruik in ander spesies. Tog word die beperkings van hierdie toets om infeksie wat spesifiek deur M. tuberculosis veroorsaak uitgelig. Ter afsluiting word hierdie studie in konteks geplaas deur 'n oorsig te gee van bogenoemde- en soortgelyke gevalle van dierlike infeksie deur mikobakterieë in Suid-Afrika. Hierdie studies bevestig dat dieremodelle steeds belangrike toevoegings maak tydens die bestudering van TB en lig veral die moontlikhede uit dat bestudering van natuulike TB in diere kan lei tot die ontdekking van nuwe insigte ten opsigte van die siekte self.

Mycobacterium bovis is the causative agent of bovine tuberculosis (BTB) which has a diverse host range. The maintenance host of BTB in South Africa is the African buffalo (Syncerus caffer). It is believed that lions get infected by feeding on infected buffalo or through wounds. The spread of the disease amongst lions has raised concern regarding the future of the animals and the impact on tourism in the country. Diagnoses of tuberculosis in free ranging wildlife is often dependent on post-mortem samples due to logistical challenges, the use of the lion specific interferon gamma release assay as an antemortem test offers a simpler methodology to testing live animals. The aim was to optimise an already developed assay by Maas et al.,2012 and to harmonise it with the Rhinoceros specific interferon gamma assay developed by Morar-Leather et al 2007. Optimisation of the interferon gamma specific ELISA included: determination of optimal concentrations for the capture and detection monoclonal antibodies; optimal concentrations for the conjugate and evaluation of alternative blocking agents. Different mitogens and incubation times were evaluated for the stimulation of whole blood as positive control in the assay. The optimum concentration for coating the plates with the capture monoclonal antibody was 2 g/ml. An optimum dilution of 1:5000 was selected for both the biotinylated detection monoclonal antibody and the streptavidin horseradish peroxidase conjugate. The assay was optimised using recombinant lion interferon gamma and the lower detection limit was calculated to be 109 pg/ml. Phosphate buffered saline with 1% bovine serum albumin was found to be Chapter 1 © University of South Africa iii a suitable blocking agent. Native interferon gamma was detected in whole blood samples from 5 lions and a 24 hour incubation time with PMA and ionomycin was selected as the optimal mitogen positive control. This assay system demonstrated good potential as an ante mortem test for the diagnosis of tuberculosis in lions. In conclusion, the assay can detect IFN- from supernatants harvested from whole blood cultures stimulated with specific antigens and mitogens / Agriculture and  Animal Health / M. Sc. (Agriculture)