Fighting TB

Watch our short animation below to see how fireflies are helping the fight against the deadly lung disease tuberculosis (TB):

TB was originally thought to be a hereditary disease until in 1869, French physician Jean-Antoine Villemin injected rabbits with material taken from people who had died of TB and showed the disease was infectious. Thirteen years later, Robert Koch purified the microorganism responsible, Mycobacterium tuberculosis, for which he won the Nobel Prize in Physiology or Medicine in 1905.

While it is over 100 years since M. tuberculosis was discovered, far from being eradicated, TB has turned into a worldwide disaster. M. tuberculosis is highly infectious, spreading from person to person through aerosols. About one third of the world’s population are believed to be infected with M. tuberculosis. There are 8.7 million new TB cases each year and 3 people die from TB every minute. Here in New Zealand we are not immune – in 2011 there were over 600 cases of TB reported.

Although antibiotics are still effective for treating the majority of TB patients, the drugs have to be taken for six months to eradicate this wiley bacterium. Unfortunately, extensively antibiotic-resistant strains of M. tuberculosis now exist and a staggering 1 in every 15 new TB cases worldwide are caused by drug-resistant strains. These cases can take 2 years to treat and cost 200 times more than regular TB, placing a huge burden on healthcare budgets. It is clear that there is a great and urgent need for new, effective antibiotics against this old foe.

96 well plate with glowing M. tuberculosis being treated with different amounts of a group of experimental compounds. Black wells are where the bacteria have been killed, while the coloured wells show the different light levels of the bacteria that are still alive (ranging from red for lots of light to blue for a little light).

96 well plate with glowing M. tuberculosis being treated with different amounts of a group of experimental compounds. Black wells are where the bacteria have been killed, while the coloured wells show the different light levels of the bacteria that are still alive (ranging from red for lots of light to blue for a little light).

Research with M. tuberculosis is hampered by their very slow growth – the bacterium takes takes four to five weeks to form colonies on agar plates. Compare this to E. coli which takes about 8 hours. To address this problem, in collaboration with colleagues at Imperial College London and funded by the Bill and Melinda Gates Foundation, we have made bioluminescent strains of M. tuberculosis which allow us to use light production as a surrogate for bacterial numbers. We now use these strains to rapidly screen for compounds that can kill M. tuberculosis. As the bacterium needs to be alive to luminesce, when they are killed they stop glowing. This means we can see whether our bacteria are dead or alive in real-time rather than in the weeks to months it takes waiting for M. tuberculosis to grow on agar plates.

We are working with colleagues from the Auckland Cancer Society Research Centre, the Department of Chemistry and the School of Biological Sciences to find new drugs to treat TB.

This work is being supported by the Maurice Wilkins Centre for Molecular Biodiscovery, the Fraser Charitable Trust, the Faculty of Medical and Health Sciences at the University of Auckland, and a University of Auckland Vice Chancellors Strategic Development Award.