Scientists have exploited the tools of genomics and bioinformatics to capture genetic fingerprints that distinguish the Bacillus anthracis used in last October's Florida bioterror attack from a closely related anthrax reference isolate. They found 60 subtle variations between the two, including differences in single nucleotides and in sets of repeated, inserted, or deleted sequences.

	Bacillus anthracis REUTERS PHOTO ARCHIVE

These markers cannot finger the exact origin of the Florida isolate, which would help nab the perpetrator of last fall's bioterrorism. But researchers from The Institute for Genomic Research (TIGR), Rockville, Md., led by geneticist Timothy Read, and from Northern Arizona University, Flagstaff, led by microbiologist Paul S. Keim, did determine that the Florida isolate and the Porton Down, U.K., reference isolate were derived from the Ames strain. That strain, isolated in 1981 from a Texas cow, was also used in letter-delivered attacks on Democratic Sens. Thomas A. Daschle (S.D.) and Patrick J. Leahy (Vt.).

The researchers have shared their data with the FBI, which is investigating last fall's anthrax outbreaks. Matthew S. Meselson, a Harvard University molecular biologist and bioweapons expert, doesn't think their data will "solve the investigation, but maybe it will point it in the right direction, provide a tip."

In previous studies aimed at aiding the FBI investigation, Keim's lab was not able to differentiate among several different Ames isolates. Then, however, Keim was searching for diversity using dozens of markers rather than the whole genome, as he and the TIGR researchers now have.

Analysis of the Florida isolate genome was published in Science online May 9 (http://www.sciencemag.org/cgi/content/abstract/1071837v1). TIGR had already sequenced the complete genome of the Porton isolate and will publish it later this year.

	Fauci UPI PHOTO SERVICE/RICARDO WATSON

Anthony S. Fauci, director of the National Institute of Allergy & Infectious Diseases, believes the anthrax comparative study can jump-start "future research on the genetic variation among anthrax bacterial strains." And, he adds, "generating genomic sequences for many different anthrax strains will allow us to distinguish among them at the single-nucleotide level."

NIAID plans to fund additional genomic analyses by TIGR and Northern Arizona University on another 14 anthrax strains or isolates. At about $140,000 per anthrax genome, whole-genome sequencing appears to offer a relatively inexpensive way of solving or deterring future bioterrorism. Still, Meselson cautions, much more work needs to be done before this approach can become a useful forensic tool.

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