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Gene research may help solve anthrax mystery

'A very powerful tool for comparison of whole genomes'

Anthrax DNA has more than 5 million unique genetic components.  

By Marsha Walton
CNN Sci-Tech

ROCKVILLE, Maryland (CNN) -- One expert predicts it will take a combination of "new science" and "good old-fashioned detective work" to find out who's responsible for the anthrax attacks that claimed five lives in the United States in the weeks after the September 11 terrorist attacks.

In a paper published this week in the journal Science, researchers at the Institute for Genomic Research (TIGR) in Rockville, Maryland, detail their contribution to the "new science" aspect of the investigation, a genetic comparison of anthrax samples.

Scientists there compared the anthrax that killed newspaper photo editor Bob Stevens in Florida with other samples of what's known as the "Ames strain" of bacillus anthracis, or anthrax. The Ames strain was originally isolated from a dead cow in Texas in 1981. This strain has since been sent to dozens, perhaps hundreds of research and defense facilities in the United States and Europe for study.

The anthrax strain that killed a Florida photo editor in 2001 is yielding clues that may help investigators. CNN's Ann Kellan reports (May 9)

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"In different labs over 21 years, they have developed mutations in their DNA sequence," says Claire Fraser, President of TIGR.

"And these are the regions we are focusing on, regions that are different, because that gives us the information we need to try to distinguish one from another," she says.

Identifying the mutations unique to each lab could eventually lead investigators to the source of the anthrax strain that killed Stevens.

"The critical thing about bacillus anthracis is that it has shown very little genetic variability," says Ronald Atlas, president-elect of the American Society for Microbiology.

"That really has been a problem in trying to fingerprint the organism," he says.

TIGR identified 60 markers, or unique genetic differences between the anthrax that killed Stevens and several other Ames samples. Of those 60, Fraser says 11 could help researchers discriminate between the Florida sample and the others. It's at least something to go on, considering that about 5 million pieces of DNA code are being compared.

Finding sources

"The fact we now have a number of sites in the genome to look at helps us eliminate some labs, and concentrate on others," says Atlas.

Anthrax spores  

But even as the science may eventually pinpoint the lab from which the Florida sample or the other deadly anthrax came, it will take law enforcement skills to determine who took the bacteria -- which could have been stolen at any time over the past two decades.

While the TIGR findings may be an early step in finding a biological terrorist, the analysis technique may pay off with less sensational medical detective work.

"It's not just anthrax strains that this is going to help with, but all infectious diseases, in finding their sources," says Atlas, who also heads the Center for Deterrence of Biowarfare and Bioterrorism at the University of Louisville.

"This allows us to compare genomes from a strain that causes disease with any number of other strains, and based on that sort of analysis, begin to differentiate. So it's a very powerful tool for comparison of whole genomes," he says.


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