�the anthrax is so sophisticated it can only have been produced with
the backing of a government.... New Scientist can reveal that the bacteria
used in the attacks is not a strain that Iraq, or the former Soviet Union,
mass-produced for weapons. In fact, it is either the same strain the US
itself used to make anthrax weapons in the 1960s, or close to it....�
--------------
New Scientist, 24 October 2001
Trail of terror
By Debora MacKenzie
Who sent the anthrax letters and are there more on the way?
THE cases just keep coming. Yet it's still not clear who's to blame for the
anthrax attacks, or whether there will be more. With little official
information so far about the nature and origin of the anthrax, claims and
counter-claims have been flying.
Prominent voices in the US charge that the anthrax is so sophisticated it
can only have been produced with the backing of a government. Their
suspicions are directed at Iraq, which is known to have made anthrax and
other bioweapons.
But New Scientist can reveal that the bacteria used in the attacks is not a
strain that Iraq, or the former Soviet Union, mass-produced for weapons. In
fact, it is either the same strain the US itself used to make anthrax
weapons in the 1960s, or close to it. Neither the strain nor the physical
form in which it has been sent out is particularly sophisticated, say
bioweapons specialists.
What may matter more than the strain is how big a batch this anthrax came
from. This could reveal not only how many more of these mailings we can
expect, but also whether the bacteria were brewed in small-scale, makeshift
labs or bigger facilities.
Work that could tell us is under way at a lab in the US. Crucial
geopolitical decisions could rest on what emerges from the electrophoresis
gels and computer programs of the lab's small band of bacterial geneticists.
Last week, Tom Ridge, President Bush's newly appointed Homeland Security
adviser, stated that the anthrax sent to Florida, NBC and Senator Tom
Daschle were all the same strain. An FBI spokesman in Florida confirmed the
widespread reports that this was the Ames strain.
But there has been confusion over what "Ames" means. The name was given to a
strain isolated at the US Department of Agriculture's veterinary lab in
Ames, Iowa, in the 1930s. This strain, which was later shared with
microbiologists around the world, still strikes cattle in the western US.
Recent American military research publications also mention an "Ames" strain
isolated from a cow in Iowa in 1980.
However, the scientists analysing the anthrax from the attacks are comparing
its DNA with a library of strains collected from all over the world. And in
this collection, what's called "Ames" has more interesting origins. It
emerged in the mid-1980s from a freezer at the Centre for Applied
Microbiology and Research, the British biodefence establishment at Porton
Down, Wiltshire.
Porton Down had acquired it from the US Army Medical Research Institute for
Infectious Diseases in Maryland. It is, say those who compiled the library,
the strain the US used when it produced anthrax weapons. That programme
ended in 1969, and the mass-produced anthrax was destroyed, although the US
and its allies kept samples. To be identified as "Ames", by these scientists
therefore, the anthrax used in the recent attacks must either be the
American military strain or one that's very similar.
So why choose this strain? "Ames is certainly a challenge to any vaccine,"
says Martin Hugh-Jones of Louisiana State University at Baton Rouge. When
lab animals immunised with the vaccine now being given to thousands of
American troops are exposed to anthrax, many are still killed by the Ames
strain.
Alternatively, the attackers may simply have wanted a strain of proven
virulence that's hard to trace, says Ken Alibek, former deputy head of the
Soviet bioweapons programme. "If I were a terrorist I would certainly not
use a strain known to be from my country," he told New Scientist.
The Soviets did not mass-produce Ames, says Alibek. Nor did the Iraqis. Like
Britain in the 1940s, Iraq favoured the Vollum strain, isolated at Oxford in
1930, which has been identified in samples from its Al Hakam plant. And the
White House reiterated last week that all anthrax mass-produced in the US
was destroyed after 1969.
Despite this, Ames would not have been have been hard to find. Samples of
the weapons strain were kept in the US and elsewhere. "The South African
collection had hundreds of different strains," Alibek points out. And Wouter
Basson, former head of the South African bioweapons programme, made several
trips to Libya after the fall of the apartheid government in 1994. Ames
could also, of course, have been obtained by someone in the US.
Important clues also come from the size of the particles used in the
attacks. According to reports last week, they had been milled down to a few
micrometres, which is optimal for causing the inhalation form of the
disease. "The terrorists at least had access to considerable know-how,"
concludes Michael Powers of the Chemical and Biological Arms Control
Institute in Washington DC. "This suggests some level of state involvement."
But Alibek dismisses claims that milling the powder this fine is too hard
for mere terrorists. "You can use readily available equipment to do this,"
he says.
His view is supported by a secret experiment last year called Project
Bacchus, in which employees of the US Department of Defense covertly
produced a kilogram of bacteria similar to anthrax. It was milled to a few
micrometres using machines available openly in the US.
Nevertheless, the attacks have caused relatively few inhalation cases so
far, which suggests that the spores were not blended with the anti-caking
chemicals used in anthrax weapons to promote airborne spread. This is the
secret of "weaponised" anthrax, says Alibek. He says sending the anthrax in
the mail is a "very primitive" way of distributing it, and suspects the
attackers don't have much material to work with.
We could soon know. Paul Keim's team at Northern Arizona University in
Flagstaff has pioneered the genetic analysis of anthrax bacilli. Recently,
says team member Kimothy Smith, they have found that some DNA regions mutate
frequently, as often as once in every 1000 cell divisions.
By comparing the amount of mutation, says Smith, "you can say with a high
degree of confidence how many bacterial generations separate an unknown
strain from closely related reference strains". Looking at which bits of DNA
have changed can also pinpoint the exact strain the unknown anthrax came
from.
And that's not all. A small batch of anthrax will undergo many fewer cell
divisions than a big batch. It's possible that the analysis could reveal
whether the anthrax came from a 50-litre fermenter of the kind Project
Bacchus obtained or the huge vats of a state-sponsored bioweapons facility.
That could reveal how big an operation the attackers had - and whether we
must expect yet more attacks.
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