Science behind anthrax letters revealed

COLLEGE PARK, Md., March 8 (UPI) -- The forensics that helped identify the anthrax strain used in a series of 2001 letter attacks is now a tool for investigators, the University of Maryland says.

The researchers, barred from discussing their work for nearly a decade, along with other key members of the science team published the first account of their pioneering work, which launched the new field of "microbial forensics," the College Park, Md., university said in a release.

The account, published in the online Early Edition of the Proceedings of National Academy of Sciences, details the multi-institutional research that the FBI used to track anthrax-laden letters to a test tube in a lab in Fort Detrick, Md.

University of Maryland bioinformatics experts conducted the computational analysis that identified four genetic mutations that together provided a unique signature of a particular colony of anthrax bacteria, the university said. The FBI subsequently determined this colony was found only in that Fort Detrick test tube.

The Maryland researchers since developed their work into a genetic fingerprinting tool available online to law enforcement tracking down other microbial suspects.

"We found unique bio-markers to help investigators track down the source of the anthrax," said Steven Salzberg, director of the University of Maryland Center for Bioinformatics and Computational Biology. "At first the tiny mutations were elusive. We thought we'd pieced together the 'jigsaw puzzle' of data very neatly, until we ended up with a few oddball bits left over. When we looked more closely, we found an extra copy of a critical gene."

Fortunately for them anthrax bacteria mutate slowly,said co-author Mihai Pop.

"If you isolate a colony of bacteria in a test tube, they'll slowly accumulate random mutations that make them distinct from any other samples of the same type of bacteria," Pop said.