TB bacterium’s code cracked

PARIS, June 11: A Franco-British team has succeeded in decoding the genome sequence of the bacterium which causes tuberculosis - a disease w...

PARIS, June 11: A Franco-British team has succeeded in decoding the genome sequence of the bacterium which causes tuberculosis – a disease which still kills about three million people a year.

Stewart Cole, head of the French team at the Pasteur Institute in Paris, said the discovery was of "crucial importance" because knowing the complete genetic make-up of the bacillus would help researchers devise new ways of combatting tuberculosis.

The research which began in 1992, has enabled the team to decipher the "complete genome sequence" of the bacillus. The work was conducted in partnership with British scientist Bert Barell of the Sanger Centre (Wellcome Trust Genome Unit) in Cambridge, England.

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The TB bacillus contains about 4,000 genes and "a very large portion of its coding capacity is devoted to the production of enzymes involved in lipogenesis or lipolysis," apparently indicating that the bacterium derives its energy from fats in the cells it infects, a report published on Wednesday said.

The naturalresistance of the "Microbacterium Tuberculosis" to a large number of anti-biotics is due to its cell wall which acts as a barrier. However analysis shows that it also has other potential defences, notably enzymes, which could enable it to resist certain treatments.

A better knowledge of these resistance mechanisms should provide clues about how better to use existing medical drugs and make it easier to develop new medicines.

The genetic decoding, which comes more than 100 years after Robert Koch first isolated the bacillus, revealed unexpectedly the existence of two new families of glycine-rich proteins codenamed PE and PPE. These could be useful in developing new vaccines and could explain why vaccines work better in some people than in others.

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"We now have the sequence of every potential drug target and of every antigen we may wish to include in a vaccine," said Douglas B Young, a British specialist in infectious disease.