Genetic adaptations of Mycobacterium tuberculosis for intracellular survival

Funded Activity Summary

Tuberculosis (TB) remains a significant global public health problem and new approaches to its treatment and prevention are urgently needed. The disease is caused by infection with Mycobacterium tuberculosis, a slow growing organism that lives within cells. How it adapts to survive in this intracellular environment is unknown. Recently the complete genome of M. tuberculosis was sequenced and new techniques developed for manipulating its genes. We plan to use these techniques to identify genes that are more active within the cells. Genes are controlled by short sequences of preceding DNA called promoters. If these promoters are randomly placed in front of readily identifiable reporter genes and inserted into a suitable host strain, it is possible to select for those promoters expressed only inside cells and then identify the promoter and its gene by sequence analysis. We plan to use two types of reporter genes. First, we shall place the M. tuberculosis DNA containing promoters before the gene for a naturally fluorescent protein within the M. bovis BCG host strain and then infect macrophages. If the promoters are switched on inside the cell, the macrophages will become green and can be selected and the promoter identified. After several rounds of selection the promoter is isolated and identified. Second, we shall select the promoters by their ability to produce a protein that is on the surface of the bacterium. We will use these intracellular genes to make better vaccines against TB. Genes that enhance intracellular survival may contribute to the virulence of the TB organism. By removing these genes we can make an attenuated organism suitable as a vaccine. We will test for reduced virulence by growth inside cells in mice. We will also use the intracellular promoter to improve the current BCG vaccine. Proteins expressed inside the cell may also be targets for new TB drugs.

Funded Activity Details

Start Date: 01-01-2000

End Date: 01-01-2002

Funding Scheme: NHMRC Project Grants

Funding Amount: $187,677.00

Funder: National Health and Medical Research Council

Research Topics

ANZSRC Field of Research (FoR)

Clinical chemistry (incl. diagnostics)

ANZSRC Socio-Economic Objective (SEO)

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Other Keywords

Disease prevention | Gene manipulation | Intracellular gene expression | Pulmonary tuberculosis | Tuberculosis | Vaccine | Vaccine technology | Virulence

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