Public Release: 

Forensics - bringing bacteria into the courtroom

American Association for the Advancement of Science

DENVER, CO - If bioterrorists are ever brought to trial, the evidence against them will depend on the painstaking work of a detective in a lab coat.

But will it be worth the effort?

Scientists at the annual meeting of the American Association for the Advancement of Science (AAAS) warn that such evidence will not be admissible unless researchers develop new molecular methods, such as genome sequencing, and adopt standardized methods and data.

"Today, there are cases that are more likely to come up in court. As a discipline, we need to be prepared," said Abigail Salyers, of the University of Illinois at Urbana-Champaign. "Let's be thinking ahead so we don't have an O.J. Simpson situation where the validity of the tests used to gather certain evidence (becomes) the focal point of a trial. We must put into place quality control and standards that provide proper validation and interpretation, so microbial evidence involving genetic information will be viewed acceptable in a courtroom."

Citing the recent attacks of anthrax sent through the mail, and the potential for other acts of bioterrorism, Salyers and her colleagues at a session held during the AAAS Annual Meeting called for the development of a comprehensive microbial forensics infrastructure.

In microbial forensics, researchers work to track down the source of a pathogen, whether in a criminal investigation of bioterrorism attacks or a study of naturally occurring disease outbreak, looking for molecular microbial signatures. These signatures are detected by measuring the polymorphisms, or variations, between microbial strains and are used to infer the origin, relationship, or transmission route of a particular isolate.

Recently, microbial forensics has been used in cases such as the alleged transmission of HIV from a Florida dentist to several patients. By sequencing viral fragments from the dentist and infected patients, they were able show that he most likely infected at least six of his patients with HIV.

And in 1993, the Japanese Aum Shinrikyo cult - later responsible for releasing Sarin gas on a Tokyo subway - tried unsuccessfully to release a variety of pathogens, including the anthrax bacterium, Bacillus anthracis.

Almost ten years later, Paul Keim, a genetics professor at Northern Arizona University, known for his work on the typing of bacterial strains, including those that cause anthrax and plague, got live cultures of the bacteria used in the Tokyo attack. Using DNA profiles, Keim's lab was able to identify the attack strain as one used in animal vaccinations, suggesting why the release had not resulted in health problems in the population in the release area.

In addition, Keim and colleagues at the Institute of Genome Research completed the genome sequence for the Bacillus anthracis isolate taken from Ray Stevens, the first anthrax letter victim. This was the first time researchers had used whole genome sequencing for the forensic identification of a particular pathogen strain.

But the recent anthrax attacks on the U.S. mail system raise a number of questions. If an individual were charged with the attacks, would the court be willing to convict him or her, using as evidence a variation in a genome sequence?

Salyers, a professor of microbiology at the University of Illinois, noted that there are well-established criteria for evaluating and interpreting the results of classical microbiology methods such as cultivation or serological testing; she suggested that similar criteria should be developed for new molecular methods such as genome sequencing.

She added that in order for any new technology to be accepted as a useful tool for deciding important questions, it is essential to determine what standards should be applied to these new technologies.

Joseph Campos, Director of the Microbiology Laboratory at Children's National Medical Center, said that quality assurance standards for microbial forensics testing are under development and that he is drawing upon his experience in overseeing clinical microbiology laboratories to help formulate the standards.


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MEDIA NOTE: Campos, Keim, Salyers, and other researchers will participate in a session entitled "Microbial Forensics: A Scientific Assessment" during the AAAS Annual Meeting in Denver, at the Denver Convention Center, 2:30 p.m. Mountain Time, Sunday, 16 February. They will brief journalists registered for the meeting at 3:00 p.m., U.S. Eastern Time, on Thursday, 14 February. Press registration is located in Room C101 of the convention center.

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