Paratuberculosis is an intestinal condition in ruminants infected with Mycobacterium avium subspecies paratuberculosis (MAP) and precedes Johne's disease, a chronic enteric disorder in ruminants caused by MAP infection. Necropsy with histopathology provides definitive diagnosis of Johne's disease and positive culture of MAP from tissues provides definitive diagnosis of paratuberculosis. To determine assay sensitivity, 85 formalin-fixed paraffin-embedded (FFPE) tissues from ruminants diagnosed with Johne's disease were tested with a commercial paratuberculosis quantitative polymerase chain reaction (qPCR) assay and had a sensitivity of 92%. To determine assay specificity, 21 FFPE tissues from animals without gastrointestinal disease combined with 13 FFPE tissues from non-ruminant animals (frog, dove, turtle, dog, and 2 cats) with non-paratuberculosis mycobacterial diseases were tested with the commercial qPCR assay and had a specificity of 100%. Slides prepared from the FFPE tissue blocks were stained with hematoxylin & eosin (H&E) and Ziehl-Neelsen's (acid fast stain), then examined for granulomatous inflammation and scored on a scale from 0-4 based on the quantity of acid fast bacteria (AFB). Digital microscopy and morphometric software were used to compute an acid fast bacteria area index (AFBAI) to evaluate a more precise correlation with the qPCR results. The quantity of AFB in tissue slides showed medium to strong correlation with the appropriate qPCR results. The results indicate that the commercial qPCR assay can be used on FFPE tissues with good results and the qPCR results have medium-strong correlation with quantitative acid fast histopathology. / Master of Science

Orientador: Fernando Rogério Pavan / Banca: Patricia Bento da Silva / Banca: Jean Leandro dos Santos / Resumo: A tuberculose (TB) é uma doença infecciosa que tem como principal patógeno o Mycobacterium tuberculosis e continua sendo um importante problema de saúde pública mundial, exigindo o desenvolvimento de estratégias para o seu controle. Em 2011 foram notificados 8,7 milhões de casos da doença no mundo. Ao longo dos anos o cenário da doença não tem se mostrado otimista, devido ao aumento de número de casos de TB multi resistente a fármacos (TB-MDR) e o surgimento de cepas de resistência estendida (TB-XDR). A pesquisa de novos fármacos, em um contexto geral, apresenta-se como um enorme desafio científico para a era moderna. Neste sentido, a Química Inorgânica Medicinal tem se mostrado uma ferramenta bastante promissora. Este trabalho objetivou a caracterização da atividade anti- M. tuberculosis intra e extracelular e a citotoxicidade de 158 compostos de coordenação com metais. A citotoxicidade usando linhagens celulares de macrófago (J774A.1) e células epiteliais (VERO) também foi investigada. Diante Os resultados demonstraram que 16 compostos apresentaram uma alta seletividade, ou seja, alta atividade contra o bacilo da tuberculose e baixa citotoxicidade frente às linhagens testadas. Quatro desses 16 compostos selecionados foram analisados quanto a atividade intracelular; dos quais 2 compostos de coordenação de Co (cobalto) mostraram-se promissores quanto a esta atividade. Com base nos resultados encontrados mais estudos serão realizados a fim de garantir a eficácia e segurança desses novos compostos de coordenação candidatos à fármacos para tratamento da tuberculose / Abstract: Not available / Mestre

Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of Johne's disease, a chronic enteritis that has a damaging economic and welfare impact on the livestock industry. Johne's disease in cattle is known to reduce milk yield and carcass value, making it of economic concern to both dairy and beef farmers. In addition, there is cause for concern regarding zoonotic transmission, as there is an unconfirmed but potential relationship between MAP infection and human Crohn's disease, which presents similar clinical symptoms. MAP is most often contracted by neonates through the faecal-oral route, but can also be spread through contact with contaminated milk and colostrum, as well as in utero. Once the host receives an oral dose, the bacteria traverse the gut epithelium and are phagocytosed by gut macrophages residing in the lamina propria and Peyer's patches. MAP are able to evade the macrophage response by resisting intracellular degradation within phagosomes. Infected macrophages respond to the infection by secreting several pro-inflammatory cytokines that drive the downstream immune response and granuloma formation. This work aimed to elucidate key early responses of bovine monocyte derived macrophages (MDM) to MAP infection, and determine the reliability of using the reference strain, K10 (which is likely to have undergone lab adaptation) to model the infection in vitro, by comparing the MDM response to K10 with the response to a recent clinical isolate, C49. At a multiplicity of infection of 5 (MOI 5), there was a significant decrease in K10 intracellular survival (~90%), compared to C49 intracellular survival, over a 24 hour infection time-course. This suggests that K10 may have lost some virulence mechanism through lab adaptation. Understanding the mechanisms of how MDM respond to these two strains could be informative for the design of targeted vaccines When further investigating the MDM response to both strains, it was found that, at MOI 5, MDM infected with K10 secreted higher levels of IL-1β and IL-10, compared to MDM infected with C49. Both cytokines are associated with mycobacterial infection and could perhaps indicate that MDM are more responsive to the K10 strain at early time-points. In addition, MDM infected with K10 produced significantly higher levels of reactive nitrogen species (RNS). RNS are antimicrobial products that can destroy invading pathogens, and have been shown to have bactericidal effects on MAP. The production of RNS could, therefore be a potential mechanism by which MDM are able to kill K10 more efficiently than C49. An additional aim of this project was to understand the importance of the route of phagocytosis in determining the outcome of MAP infection. MDM express several phagocytic receptors, including Fc receptors (FcRs), complement receptors (CR), Ctype lectin receptors and scavenger receptors. This project mainly focused on the role of the mannose receptor (MR) on bacterial uptake and downstream immune responses, as past studies have suggested that other species of mycobacteria such as M. tuberculosis, target the mannose receptor in order to regulate macrophage immune responses. Blocking the MR reduced intracellular survival for both strains of MAP; however, the mechanism by which the MR influences intracellular survival remains poorly understood The effect of opsonisation on MAP prior to uptake by phagocytic cells was also investigated, as presence of opsonins, such a complement proteins and antibody, can change the mechanism by which pathogens are phagocytosed. MAP were incubated in serum from either MAP- negative or MAP- positive cattle, prior to infection and the percentage uptake and survival assessed by performing colony counts. Opsonisation in serum from Johne's negative cattle resulted in marked increase in MAP uptake but not intracellular survival, whereas opsonisation in serum from Johne's positive cattle did not increase uptake but decreased the intracellular survival rate by 24 HPI. This finding highlights a potential protective role of antibody early in the infection process, and could significantly impact how the infection is modelled in future, as anti-MAP antibody may be present in contaminated milk at the point of infection. Taken together, the data presented in this thesis show that bacterial strain has a significant impact on MDM response to MAP infection, which may have important implications for the interpretation of previous studies and the design of future studies investigating host-pathogen interactions in the context of paratuberculosis. Additionally, this work has shown that RNS production and the mechanism of uptake can affect intracellular survival rates, and although this needs further investigation, the findings could have implications for the design of future vaccines.

The validity of Johne??s disease herd status programs and on-farm disease control programs that rely on established ??cutpoints?? (e.g., S/P ratios) for ELISA serological tests such as the HerdChek?? (IDEXX Laboratories Inc., Westbrook, Maine) may be susceptible to varied seasonal test accuracy. An observed depression in the proportion of a large central Texas dairy herd classified as ??positive?? during the months of July and August led to our investigation. We hypothesized that there exists a seasonal variability in serological response to Mycobacterium avium subsp. paratuberculosis that is directly related to heat stress. We further hypothesized that a reciprocal response may occur during periods of heat stress that results in a greater risk of fecal shedding in subclinically-infected animals. Starting in October 2002, we invoked a testing regime that included multiple testing of 720 individual adult cows over each of four seasons including spring, summer, fall, and winter. We collected serum on a cyclic, monthly basis from three random groupings of cows, and, based on the ELISA results, collected fecal samples from the 20% of cows with the highest S/P ratios. We continued to sample in this manner for the period of one year and at the end of that period, analyzed the serum en masse. The ELISA outcome values were treated both as categorical and continuous variables (e.g., S/P ratio). The potential lagged effects of heat stress on S/P ratio, as well as the potential for a change in test result (negative to positive or vice versa) due to heat stress were assessed. The results for fecal culture were analyzed on a categorical scale and were compared to the ELISA results to explore the possibility of a reciprocal response. In the present study, we did not observe any of the significant seasonal effects of heat stress on S/P ratios and proportion seropositive to MAP that were observed in the historical (and less valid) cross-sectional time-series data conducted in 2001. In addition, we found no evidence to support a hypothesis linking seasonal heat stress to the risk of fecal culture positivity for the causative bacterium for Johne??s disease.

This study explored the use of a biosecure, static composting structure to inactivate MAP. In Experiment #1, it was concluded that composting is unlikely to achieve temperatures necessary to inactivate MAP associated with cattle mortalities and that M. smegamatis is an unlikely surrogate for MAP. This study also used the same system to explore changes in the microbial community in mortality compost after exposure to thermophilic temperatures. As high-throughput sequencing technologies advance, it is possible to characterize microbial communities in environments with a high degree of resolution. In Experiment #2, as members of Clostridia were present at temperatures > 55°C, it appears that anaerobic conditions existed within regions of the compost. Extreme temperatures and non-homogeneous high moisture conditions resulted in spatial distribution of temperature in a biosecure, static composting system, which failed to meet conditions necessary for complete composting and pathogen reduction.

Crohn’s disease (CD) is a chronic inflammatory bowel disease, primarily affecting the young, which causes marked morbidity and reduced quality of life. Currently there is no cure for CD, and the causes of this disease are poorly understood. In ruminants, Johne’s disease (JD) is characterised by chronic intestinal inflammation similar to CD and is caused by the pathogen Mycobacterium avium subspecies paratuberculosis (MAP), which invades and replicates within the phagocytes of infected animals, leading to chronic disease. There is increasing molecular and microbiological evidence of Map bacteria in CD patients. However, little is known regarding the role of Map in the aetiology of CD. This thesis demonstrated that a human isolate of Map traffics through THP-1 human monocytes via a similar path to that taken by pathogenic mycobacteria. Flow cytometry demonstrated that Map are phagocytosed via a cholesterol-dependant mechanism, potentially mediated by a cell wall constituent. Once internalised, live Map reside in cholesterol-rich areas of the cell. These compartments exhibit reduced acidity compared to the compartments containing killed-Map, and have atypical retention of markers including the late endosomal marker Rab 7 and cellular TACO protein. Both of these markers were also present on phagosomes of pathogenic mycobacteria, where they interrupt fusion of the compartment with lysosomes. This was confirmed by visualisation of these proteins on phagosomes containing M. bovis,a known mycobacterial pathogen. Cholesterol depletion using simvastatin affected Map persistence in THP-1 cells at 1 and 2 weeks post infection, a finding similar to other studies with M. tuberculosis. Spheroplast-like forms were evident after long term culture of Map with THP-1 monocytes, visualised by light and electron microscopy. These were similar to forms observed in peripheral blood leukocytes from a CD patient. Collectively, these results support the hypothesis that Map may be involved in the aetiology of at least a subset of CD cases.

This study explored the use of a biosecure, static composting structure to inactivate MAP. In Experiment #1, it was concluded that composting is unlikely to achieve temperatures necessary to inactivate MAP associated with cattle mortalities and that M. smegamatis is an unlikely surrogate for MAP. This study also used the same system to explore changes in the microbial community in mortality compost after exposure to thermophilic temperatures. As high-throughput sequencing technologies advance, it is possible to characterize microbial communities in environments with a high degree of resolution. In Experiment #2, as members of Clostridia were present at temperatures > 55°C, it appears that anaerobic conditions existed within regions of the compost. Extreme temperatures and non-homogeneous high moisture conditions resulted in spatial distribution of temperature in a biosecure, static composting system, which failed to meet conditions necessary for complete composting and pathogen reduction.

Graduation date: 2005

Made available in DSpace on 2014-06-11T19:27:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-07-16Bitstream added on 2014-06-13T20:16:30Z : No. of bitstreams: 1 souza_pc_me_arafcf.pdf: 1133784 bytes, checksum: 02f70c3dafbe0953dabe3934d0e053a7 (MD5) / A tuberculose (TB) é uma doença infecciosa que tem como principal patógeno o Mycobacterium tuberculosis e continua sendo um importante problema de saúde pública mundial, exigindo o desenvolvimento de estratégias para o seu controle. Em 2011 foram notificados 8,7 milhões de casos da doença no mundo. Ao longo dos anos o cenário da doença não tem se mostrado otimista, devido ao aumento de número de casos de TB multi resistente a fármacos (TB-MDR) e o surgimento de cepas de resistência estendida (TB-XDR). A pesquisa de novos fármacos, em um contexto geral, apresenta-se como um enorme desafio científico para a era moderna. Neste sentido, a Química Inorgânica Medicinal tem se mostrado uma ferramenta bastante promissora. Este trabalho objetivou a caracterização da atividade anti- M. tuberculosis intra e extracelular e a citotoxicidade de 158 compostos de coordenação com metais. A citotoxicidade usando linhagens celulares de macrófago (J774A.1) e células epiteliais (VERO) também foi investigada. Diante Os resultados demonstraram que 16 compostos apresentaram uma alta seletividade, ou seja, alta atividade contra o bacilo da tuberculose e baixa citotoxicidade frente às linhagens testadas. Quatro desses 16 compostos selecionados foram analisados quanto a atividade intracelular; dos quais 2 compostos de coordenação de Co (cobalto) mostraram-se promissores quanto a esta atividade. Com base nos resultados encontrados mais estudos serão realizados a fim de garantir a eficácia e segurança desses novos compostos de coordenação candidatos à fármacos para tratamento da tuberculose / Not available

Paratuberculosis represents a major problem in farmed ruminants and at the present is considered a potential zoonosis. The disease is caused by Mycobacterium avium subsp. paratuberculosis, and susceptibility to infection is suspected to have a genetic component. Caspase recruitment domain 15 (CARD15) gene encodes for a cytosolic protein implicated in bacterial recognition during innate immunity. Crohn's disease (CD) is an idiopathic inflammatory bowel disease in humans comparable in many features to bovine paratuberculosis involving an abnormal mucosal immune response. The association between mutations in the CARD15 gene and increased risk of Crohn's disease has been described. The objective of this candidate gene case-control study was to characterize the distribution of three polymorphisms in the bovine CARD15 gene and test their association with paratuberculosis infection in cattle. Three previously reported single nucleotide polymorphisms (E2[-32] intron 1; 2197/C733R and 3020/Q1007L) were screened for the study population (431 adult cows). The statistical analysis resulted in significant differences in allelic frequencies between cases and controls for SNP2197/C733R (P < 0.001), indicating a significant association between infection and variant allele. In the analysis of genotypes, a significant association was also found between SNP2197/C733R and infection status (P < 0.0001); cows with the heterozygous genotype were 3.35 times more likely to be infected than cows with the reference genotype (P = 0.01). Results suggest a role for CARD15 gene in the susceptibility of cattle to paratuberculosis infection. These data contribute to the understanding of paratuberculosis, suggest new similarities with Crohn's disease and provide new information for the control of bovine paratuberculosis.