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Title: Evaluation of the immunological mechanisms induced by mycobacteria and the potential effect this may have on immunity induced by tuberculosis vaccines
Author: Poyntz, Hazel Claire
ISNI:       0000 0004 2747 8012
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2012
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The efficacy of Bacille-Calmette Guerin (BCG) vaccination in protection against pulmonary tuberculosis (TB) is highly variable between populations. One possible explanation is increased exposure of certain populations to non-tuberculous mycobacteria (NTM). Given the variable efficacy of BCG an improved vaccine against TB is required. The novel TB vaccine MVA85A has shown promising results, however, the immunogenicity of the vaccine is reduced when it is administered in the Expanded Programme on Immunisation (EPI) schedule. This thesis aims to explore: (A) the effect of exposure to NTM on the level of protection afforded by BCG vaccination against Mycobacterium tuberculosis (M. tb) and (B) the immunological mechanisms behind EPI interference with MVA85A. The effect of M. avium (MA) exposure via systemic and oral routes on the efficacy of BCG was tested using M. tb aerosol infection in a mouse model. The adaptive immune response was profiled in BCG vaccinated mice with and without exposure to MA pre- and post- M. tb infection. The results showed BCG efficacy could be enhanced by exposure to dead MA by a systemic route; T helper 1 and T helper 17 responses were associated with increased protection. In contrast, BCG efficacy may have been reduced by exposure to live MA by the oral route; T helper 2 and regulatory T cells were associated with reduced protection. To answer the second aim MVA85A was co-administered to mice with aluminium adjuvants or aluminium-containing vaccines to replicate the effect of co-administration in the EPI schedule; the adaptive immune response was profiled. T helper 2 and regulatory T cell responses induced by aluminium-containing vaccines were associated with a reduction in the immunogenicity of MVA85A.
Supervisor: McShane, Helen Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Clinical microbiology ; Infectious diseases ; Immunology ; Tropical medicine ; Vaccinology ; non-tuberculous mycobacteria ; bacillus calmette-geurin ; pulmonary tuberculosis ; Mycobacterium tuberculosis ; adaptive immunity ; T cells