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Thursday, 19 July, 2001, 18:05 GMT 19:05 UK
Pneumonia bug decoded
Stethoscope, BBC
Pneumonia may develop resistance to treatment
By BBC News Online's Ivan Noble

Streptococcus pneumoniae, the bug responsible for pneumonia, is the latest organism to have its complete genetic sequence decoded.

Streptococcus pneumoniae
2,236 genes
2.16m base pairs
Most common cause of acute respiratory infection
The achievement should speed up the development of new drugs to combat the killer disease.

"It basically kickstarts everybody's science," Hervé Tettelin, lead scientist on the sequencing project, told BBC News Online.

Modern drug researchers look for genetic weaknesses in bugs like S. pneumoniae, and having the whole genetic sequence available should make the job easier.

Shotgun method

Dr Tettelin is part of the team at the Institute for Genomic Research (Tigr) in the United States which carried out the decoding.

This organism appears to be a real champion at using all sorts of sugars

Hervé Tettelin
They used a method known as shotgun sequencing, which involves blasting apart the bug's DNA to read the code, and then using powerful computers to work out how to fit it back together and make sense of it all.

Some researchers have sought to question the accuracy of this sequencing approach - they did so when it was used by a commercial company to decode the three billion biochemical "letters" that describe human life.

But Dr Tettelin is confident that the technology has done a more than adequate job on the pneumonia bug.

Finding genes in human DNA is extremely tricky, because most of our DNA is so-called junk DNA and only a small percentage of it actually forms genes. But in bacteria like S. pneumoniae, 85-90% of the DNA forms genes and little, if any of it, is junk.

Resistance danger

The Tigr team has used the sequence information to provide more valuable clues for drug researchers. They predict a list of proteins which they expect will be exposed on the surface of the bug, thereby offering a targets for new drugs.

S. pneumoniae is responsible for other infections besides pneumonia.

Depending on where it is found in the body, it also causes meningitis and ear infections. It is carried by an estimated one-third of the population.

Infections are normally treated with penicillin, but the bug has the potential to develop resistance. Researchers calculate that it is responsible for three million deaths a year worldwide.

The genetic sequence also provides a clue to why the pathogen is so versatile.

"This organism appears to be a real champion at using all sorts of sugars," said Hervé Tettelin. "This versatility at using sugars gives it an advantage over other organisms competing in the same niche."

Details of the research are published in the journal Science.

See also:

07 Jul 01 | Sci/Tech
Dispute over number of human genes
17 Jul 01 | Health
Crucial cancer genes identified
01 Aug 01 | Sci/Tech
Genome data called into question
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