Gene Sequencing To Further TB Research

An international project involving scientists from the United States and South Africa has made a major step forward in the ongoing global fight against tuberculosis (TB).

By sequencing the genes of the most deadly strains of the bacteria responsible for TB, researchers from both the Broad Institute—a joint Harvard and MIT research organization—and the University of KwaZulu-Natal in South Africa hope they have opened the door to a new way of studying TB and its effects.

Megan Murray, an associate professor at the Harvard School of Public Health (HSPH), co-led the project, which has been ongoing for 15 months. Willem Sturm, the Interim Dean of the Nelson Mandela School of Medicine in South Africa, was the project’s other leader.

The project focused on multidrug-resistant tuberculosis (MDR-TB) and a strain of extensively drug-resistant tuberculosis (XDR-TB) that had recently killed 45 people in KwaZulu-Natal.

The collection and identification of the strains took place in South Africa, while the scientists at the Broad Institute incubated and sequenced the genes.

Although TB genes have been sequenced before, this is the first time that three different strains of the disease have been sequenced at critical sections of the genome, enabling scientists to examine their genetic differences

“It’s comparing like with like. We can see how one strain is more able to cause disease and also how drug resistance is maintained by these different types,” said HSPH Associate Professor Eric J. Rubin, who researches TB at the Broad Institute.

TB is a disease caused by the bacteria Mycobacterium tuberculosis. At least two billion people worldwide have been exposed to the bacteria, although only some of the exposed develop the disease.

One reason TB has become so widespread is the bacteria’s ability to resist drug treatment.

This project hopes to act as a model for future research on the disease, Murray said. To this end, she and her team decided to make their genetic data available online.

“This is a big step forward,” Murray said. “We are trying to detect mutations that allow organisms to become resistant—what kinds of things might happen in the evolution of these organisms that allows them to be so successful, that allow resistance to happen in the first place.”

The genetic sequencing data can be used to study what mutations cause to happen to the bacteria, but the strains tested in this research represent only a few types of TB. Currently, work is being done in Russia, Peru, and other regions of South Africa to identify other strains for sequencing.

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