The Federal Bureau of Investigation (FBI) is expected to soon disclose what evidence led them to suspect Bruce Ivins, a microbiologist at the US Army Medical Research Institute of Infectious Diseases (USAMRIID) at Fort Detrick in Frederick, Maryland, of the 2001 postal anthrax attacks. But an emerging technology, available only in the past couple of years, is thought to have played a part.

The T5000 Biosensor System, created by Ibis Biosciences of Carlsbad, California, allows researchers to identify a microbe from an unknown sample, then match it to a particular strain of a pathogen. “This creates a high-resolution signature for microbial and human forensics,” says David Ecker, the chief scientific officer at Ibis.

Comparing Bacillus anthracis strains allows investigators to trace samples back to particular laboratories. Credit: Janice Haney Carr

Ecker confirmed that his firm has provided the equipment to the FBI, the Department of Homeland Security and researchers at the USAMRIID facility. He declined to discuss the Ivins investigation itself.

Following the trail

Immediately after the 2001 anthrax attacks, in which letters containing spores were mailed to news media offices and to members of Congress, laboratories around the United States raced to sequence the strain of Bacillus anthracis involved. It was quickly designated as the strain known as Ames, and traced back to the Fort Detrick facility1. In 2003, the genome sequence of the Ames strain was published by a team led by the Institute for Genomic Research in Rockville, Maryland2.

At the same time, investigators were looking for new methods to link the postal samples to existing virus isolates, which led them to Ibis. The T5000 works by using a mass spectrometer to measure the total mass of a sample, along with a breakdown of the number of each of the four nucleotides in the sample. The type of microbe can be identified and the nucleotides compared to known isolates, thereby specifically linking one sample to another. It has been used for emerging pathogens such as severe acute respiratory syndrome (SARS) and influenza3.

Suspected methods

The technology was originally developed in about 1999 for clinical tests by Isis Pharmaceuticals, also of Carlsbad, which then formed the subsidiary Ibis. Abbott Molecular of Des Plaines, Illinois, has since purchased almost 20% of Ibis. Company officials say that the FBI contracted with the firm in 2002, with the first forensic work being done in 2003. Fort Detrick received its first T5000 equipment in August 2005, and the FBI in late 2006.

Ecker says the Ibis system has not yet been used as evidence in either a criminal or civil trial.