Bovine TB: Research project summary
Project SE3226: Development of tools to study immunopathology in badger tuberculosis.
Project duration: 1 year
The aim of this project was to assess the immune mediators that contribute to lesion development, contain mycobacteria or inhibit bacterial proliferation in badger TB. This information will help understand how TB pathology develops in the badger and provide a possible insight into the immune response to BCG vaccination. There were two objectives to this study.
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The first was to study granuloma in lesions of BCG vaccinates vs. non-vaccinates. The technique of immunohistochemistry was used where antibodies to defined cell markers are used identify pathological changes that take place in TB affected tissues. Material from the Republic of Ireland (RoI) BCG vaccination programme was used. A wide range of immunological markers were used on samples but reactivity was only found to three cell types (T cells, B cells and macrophages). Further markers are required in order to be able to fully utilise this approach for the study of pathogenesis in the badger. Whilst there were no differences in the T cell or macrophage profiles between vaccinated and non-vaccinated individuals, it appears that there could be a greater number of B cells associated with the granulomas in vaccinated badgers.
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The second was the characterisation of disease stage in badgers using material derived from the RoI BCG vaccine trials. A classification system for lymph node granulomas by stage of lesion advancement was developed. The size and distribution of granulomas and number of mycobacteria within lesions were evaluated. It was found that there were three main areas of difference between vaccinated and challenged badgers to those that were challenged with M. bovis alone. Animals that had been vaccinated with BCG showed less mineralization and necrosis than non-vaccinated samples but also had more of a specific immune cell type than non-vaccinated samples. A summary of findings between tissue types is found in the report. To help assess the effects of vaccination on wild badgers this classification system will be applied to the vaccine trial currently being undertaken using parenteral vaccination using BCG in the UK.
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Page last modified:
July 7, 2008