Despite promise, genetic analysis so far failing to help anthrax investigation

by Laura Meckler
The Associated Press

WASHINGTON - Sophisticated genetic fingerprinting that investigators hoped would help crack the anthrax case has yet to yield results. With the most promising avenue gone, the FBI is expanding its scientific probe, law enforcement officials said yesterday.

"There's still potential out there," a senior law enforcement official said. "We are not at the point yet of being able to say it's over, done, there's nothing there."

Eight months after the attacks by mail killed five people, standard investigative techniques have yet to produce a breakthrough in the case.

The hope was that genetic matching could help determine which of about a dozen laboratories that have the Ames strain of anthrax, the type used in the attacks, was the source of the deadly microbes.

Scientists say it's still possible that genetic analysis will help, but they are increasingly pessimistic.

"I did think this would be a fairly straightforward case when this first came out," said Mark Whellis, a microbiologist at the University of California-Davis who serves on the Federation of American Scientists' Working Group on Biological Weapons. "Now, seven or eight months out from attacks, with no apparent forward movement in the case, it is quite distressing. It makes me pessimistic about ever resolving it."

Conventional genetic fingerprinting, tried early on, didn't work because the genetic makeup of anthrax changes very little from generation to generation, so various samples of the Ames anthrax are virtually identical.

But in January, researchers unraveling the entire genetic code of anthrax made an important breakthrough: They found small differences between the anthrax mailed to Florida, where the attacks first surfaced, and anthrax from a lab in England, a standard source of the microbe.

These researchers turned their work over to scientists in Arizona who are working for the FBI and have on hand hundreds of samples of anthrax, from every lab known to house the bacteria. The idea was to compare the anthrax held at each of these labs to the attack samples. If anthrax at a particular lab was more similar than others to the attack anthrax, that would suggest that this lab might be the source.

With this research in hand, scientists knew precisely where to look among the five million units of DNA that make up the genetic code of anthrax.

But that genetic fingerprinting failed to narrow the field because they were unable to find the same differences among samples in hand, FBI spokesman Bill Carter said.

The problem could be that the anthrax used in the attacks evolved genetically after it was taken from the lab, explaining why it no longer matches the lab samples, said Philip Hanna, an anthrax researcher at the University of Michigan Medical School. Or, he said, it's possible that it came from a lab that has not provided a sample to the government, although authorities have subpoenaed anthrax samples from all labs known to have the microbe.

As a result, researchers working for the FBI are taking a step back, genetically speaking. They are unraveling the genetic code of the first anthrax sample that was used in laboratory work, which produced all the other samples now scattered around the country, so they can look for other tiny differences that may exist as anthrax changes over time, said the senior law enforcement official, speaking on condition of anonymity.

It's unclear whether that will be any more successful.

"The deeper you have to delve into it, and you keep coming up negative, that's one more hope gone," Hanna said. "There was optimism. It was based on hope and not fact, and when the facts come in and they don't work out, you're disappointed."

Timothy D. Read, whose work at the Institute for Genetic Research in Rockville, Md. provided the FBI with its first genetic roadmap for anthrax, said it is disappointing that the differences identified by his team did not pinpoint the source. But he said additional research could be helpful.

"I don't think it's completely impossible," he said.

Read's genetic analysis began more than two years ago, when he and colleagues began studying the genetic code of an anthrax sample from the British biodefense laboratory at Porton Down in England. Porton Down had received its sample more than a decade earlier from the Army lab at Fort Detrick, Md.

In October, after the anthrax attacks, the National Science Foundation gave Read's institute $200,000 to expand its work and map the genetic code of the anthrax used in the attacks.

Read finished his work comparing the genetics of each sample in January and gave the data to Dr. Paul Keim at the University of Arizona, who is doing the genetic analysis for the FBI.