Rockville firm's scientists find genetic fingerprints for anthrax

Discovery may help trace source of deadly bacteria

January 22, 2002|By NEW YORK TIMES NEWS SERVICE

In a break for anthrax investigators, scientists say they have discovered genetic fingerprints that may help determine which of many laboratories is the likely source of the microbe used in the attacks.

The advance is a byproduct of a scientific effort to decode the full DNA or genome of the Ames strain of anthrax, the type used in letters that began circulating through the mail in the fall, killing five people.

Scientists at the Institute for Genomic Research in Rockville, a private group working for the government, say they have found a small number of genetic differences between the anthrax in the Florida attack and a standard source of the Ames strain.

Conventional methods of genetic fingerprinting have failed to distinguish among the various stocks of Ames anthrax possessed by different laboratories. The new points of difference could allow investigators to match the attack anthrax to one of the Ames samples they have collected from a dozen or so laboratories here and abroad, and perhaps identify where the germs were obtained.

The genetic analysis of anthrax stocks "might give us the edge" in cracking the case, said a senior law enforcement official, speaking on condition of anonymity.

Scientists have never before compared two full genomes of an organism at every unit of its DNA, nor done so as part of a criminal investigation, institute scientists say. The tool could prove important for law enforcement and fighting terrorism, shedding light on subtle relationships among germs that otherwise appear identical.

The advance comes as the FBI has made little headway, and plans this week to raise the reward for information in the anthrax case.

Anthrax, like other bacteria, grows by dividing into two cells that are generally identical except for the rare errors made in copying the 5 million units of DNA that make up its genome, its complete set of heredity information.

When the attacks began, investigators hoped to identify the source of the bacteria by comparing it with a collection of nearly 100 anthrax strains gathered around the world and curated by Martin E. Hugh-Jones at Louisiana State University and Paul Keim of Northern Arizona University.

Keim, Hugh-Jones, Paul J. Jackson of the Los Alamos National Laboratory and others developed a genetic identification test for anthrax strains, similar to the DNA fingerprinting test used in human forensic cases. They discovered eight points of genetic difference, which they made the basis for distinguishing strains.

When the attack germs were analyzed, all turned out to belong to the Ames strain. But this proved of little help because the Ames strain had been widely distributed to labs in this country and abroad.

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