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Last Updated

11 Jun 2003

Source: Washington Post, November 25, 2001.

Deadly Anthrax Strain Leaves a Muddy Trail

By Steve Fainaru and Joby Warrick, Washington Post Staff Writers

For more than a month, federal investigators have stalked the poisonous anthrax strain used in the recent terrorist attacks. The search has led to culture collections and research labs, to microbiologists and veterinarians, to anywhere and anyone who might have come in contact with the Ames strain.

But with each new case, the mysteries surrounding the distribution of Ames are only deepening. Once thought to be accessible to thousands of researchers, the strain now appears to have circulated in only a small universe of laboratories. One of its main distributors, according to scientists, was the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) at Fort Detrick, Md., which used Ames to test vaccines that could protect U.S. troops in case of a biological attack.

In following the trail, investigators have had to face the possibility that Ames may have slipped through an informal network of scientists to Iraq, which sought the strain from a British biodefense institute in 1988 but whose application was rejected because of concerns that it would be used to manufacture biological weapons.

Understanding the distribution of the Ames strain may be critical to the government's search for those behind the attacks that have killed five people, infected 13 others and disrupted the federal government. In the latest case, that of a 94-year-old Connecticut woman who died Wednesday after contracting inhalation anthrax, federal investigators said DNA testing showed that the bacteria was indistinguishable from the strain that appeared in the attacks in Florida, Washington and New York.

Those attacks involved the Ames strain, a virulent anthrax bacteria named for the Iowa city where it was originally isolated, according to an Oct. 25 statement from Tom Ridge, the White House director of homeland security. But identifying the type of anthrax from among the 89 known genetic strains has done little to clear up confusion within the government and the scientific community over the history of the Ames strain, how many scientists had access to it and how it might have circulated.

When the attacks began, there was speculation that thousands of labs might have had access to Ames, but that number has been knocked down by anthrax experts. Philip C. Hanna, a microbiologist at the University of Michigan, said: "I'd put it . . . between 10 and 24."

Paul Keim, who has done genetic mapping of anthrax strains at Northern Arizona University and is reportedly assisting the FBI with the investigation, said he was uncertain of the number of labs with Ames but described it as "a pretty small list" that he thought was "very discoverable."

Only a few facts have been clearly established. The strain of Bacillus anthracis that became known as Ames was first isolated decades ago from a diseased cow near Ames. A natural or "wild" strain, Ames was recognized relatively early for its virulence and for its ability to resist vaccines.

Scientists in America's biological weapons program chose a different strain, called Vollum 1B, as the lethal ingredient in U.S. anthrax weapons in the 1950s and 1960s. But in the late 1970s, following the dismantling of the program by President Richard M. Nixon, Fort Detrick's microbiologists turned to the Ames strain to develop and test tougher anti-anthrax vaccines to protect against biological weapons being built in the Soviet Union.

"There was a whole new interest because of what the Soviets were doing," said Joseph V. Jemski, who ran animal experiments at Fort Detrick. "I remember we began working with three strains: One from Colorado, another from Texas -- and Ames."

Fort Detrick's work established Ames as something of a gold standard, a hardy strain that helps biologists gauge the effectiveness of potential vaccines and treatments. Soon, other researchers also became interested in Ames, and Army scientists would help them obtain it.

"We were all just doing science," said David R. Franz, a scientist at Fort Detrick in the early 1980s and now vice president of the Chemical & Biological Defense Division of the Southern Research Institute, recalling an era of scientific openness that followed the secretive days of the bioweapons program. "Our biowarfare era was over, and we were doing a lot of work with academia and studying the variant strains. Things just weren't as tight as they became" after new federal security guidelines on transfers went into effect in the late 1990s.

Biologists familiar with Ames identified USAMRIID as the strain's major distributor. "USAMRIID is the one that handled most of the distribution of this strain," said Keim. "Surely they would know" who received it.

Martin Hugh-Jones, an anthrax expert at Louisiana State University who maintains a global database of anthrax outbreaks for the World Health Organization, concurred that it was relatively simple in the past to obtain anthrax cultures from USAMRIID.

"They kept the stuff there, and if you needed a culture, you called up Art" -- Col. Arthur Friedlander, USAMRIID's senior military research scientist, Hugh-Jones said.

In some cases, the bacteria delivered to researchers were genetically altered to prevent their use as a weapon or make it less hazardous. Duke University researcher Ken Wilson, for example, said he obtained the Ames strain from USAMRIID in the early 1990s but only after the organism had been stripped of its ability to produce deadly toxins.

Other researchers received the bug in its virulent form. One such recipient was at Fort Detrick's British counterpart, the Chemical Defense Establishment at Porton Down, near Salisbury, England. Peter Turnbull, a former Porton Down microbiologist, said the institute also was testing vaccines that would protect troops against various anthrax strains.

British scientists in turn shared the Ames strain with other researchers. In the mid-1990s, Porton Down sent a packet containing Ames spores to Hugh-Jones, and also to a "very few" others, said Turnbull, who declined to name them.

"It wasn't random," said Turnbull. "We would know the other person's bona fides. It was not spread around promiscuously."

Investigators are now hoping that retracing the movement of Ames will help lead them to the person or group behind the anthrax mailings of September and October. Since mid-October, FBI agents have visited universities, pharmaceutical laboratories, hospitals and veterinary centers to find out who may have had access to the strain.

Some researchers, such as Louisiana State University's Hugh-Jones, have been subpoenaed and questioned for hours about the possibility that Ames spores might have been lost or stolen. Hugh-Jones said he has turned over laboratory documents to the FBI and insisted his lab kept the Ames strain under tight control.

"Nobody got it from us; it stopped with us," he said.

In fact, some anthrax experts believe that it may be impossible to learn exactly how many researchers have Ames. Genetic differences among anthrax strains are slight, and until the advent of genetic typing in recent years, the labeling of strains was often sloppy. It is possible that Ames bacteria ended up in many other laboratories, but under a different name. Perhaps the strain even reached Iraq, or another state with a biological weapons program, some scientists say.

"I don't think anyone had heard of [Ames] before we published our vaccine results" in the 1980s, Turnbull, the former Porton Down scientist, said. "There doesn't appear to be a history of the strain previous to this. Perhaps it existed as stock on a shelf somewhere. Someone isolates a strain -- we believe in this case it was from a cow from Ames, Iowa -- and it's labeled 'Iowa cow' and placed on a shelf somewhere."

Because of the imprecise labeling, some experts say that anthrax strains that were widely distributed should be analyzed to see if they match genetically the strain used in the attacks.

Of the seven strains sent to Iraq by the American Type Culture Collection in the late 1980s, for example, none was labeled "Ames." But Kimothy L. Smith, a member of Keim's genetic analysis team that reportedly has been helping the FBI investigation, said he did not believe that all the strains sent to Iraq had been studied and compared to known varieties.

"It's a tower of Babel when it comes to nomenclature," said one scientist familiar with the Iraqi shipments. "Much of what is out there in the biological world is not well identified."

Given Iraq's interest in obtaining the Ames strain -- and given the lax controls over pathogen movement in the past -- some experts are convinced that Baghdad has Ames. "The probability that they don't have the strain is near zero," said a microbiologist who has studied Ames.

But others are hopeful that the Ames microbes used in the attacks will turn up closer to home, leaving a clear trail to the perpetrators.

"Basically, if some guy's got this culture on his dirty clothes or on his bench top, he'll have some explaining to do," said Hugh-Jones. "It's like owning a pistol that was used in a homicide."

Staff researchers Alice Crites, Bobbye Pratt and Mary Lou White contributed to this report.