Discovery could protect people from bioterrorist attack
By
Maggie Fox
Sept. 4
A
vaccine against ricin, one of the deadliest toxins known, works in mice
and may work to protect people in case of a bioterrorist attack, U.S.
researchers said on Wednesday.
Ricin,
which comes from the castor bean, is considered a likely biowarfare or
bioterrorist agent and is on the Center for Disease Control and Preventions
B list of agents considered a moderate threat.
THE
RESEARCHERS, at the University of Texas Southwestern Medical Center at
Dallas, came up with the vaccine as part of their work using the potent
toxin to fight cancer. But they hope the government will fund further
studies to develop the vaccine to protect troops or civilians against
biowarfare.
Ricin, which comes from the castor bean, is considered a likely
biowarfare or bioterrorist agent and is on the Center for Disease Control
and Preventions B list of agents considered a moderate threat.
It is most known as the poison used to assassinate Bulgarian exile
Georgi Markov in London in 1978, delivered by a special needle-tipped
umbrella.
What is incredibly frightening about ricin is that it is so easy to
make. It is so easy to stockpile, said Dr. Ellen Vitetta, who led the
study.
You dont have to be a brilliant chemist. You basically just grind
up the castor beans. Castor beans grow everywhere in the world. There are
stockpiles in many countries. It is extremely lethal to people and it been
used in espionage for years.
The toxin can be put into food, water or even made into an aerosol
and sprayed. It is broken down quickly in the body and is almost impossible
to trace.
A very small dose of this is
quite lethal for humans and the symptoms are very disconcerting, Vitetta
said in a telephone interview. You feel flu-like for a few days and then
you are dead. Its terrible.
Some vaccines have been tried but none has worked well. Vitetta said
her teams appears to be safe and potent in mice.
Vaccines against toxins are not unusual the tetanus vaccine
stimulates the body to produce antibodies against the toxin produced by the
Clostridium tetani bacteria.
Antibodies are proteins that can hook onto a target such as a
bacteria or virus, stopping it from doing any harm and holding it in place
until immune system cells can come along and dispose of it.
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Vitettas team
took a similar approach to the ricin toxin, they report in the Sept. 10
issue of the journal Vaccine.
The actual toxin that we are talking about has two proteins linked
together, she said. The B chain B stands for binding binds it to all
cells of higher organisms. Once it is bound, the A chain destroys all the
ribosomes in cells.
This stops all protein production and shuts the body down.
They made a genetically engineered version of the toxin that lacks
the A chain and some other pieces, so it is harmless to cells.
The mice they tested it on were vaccinated with the genetically
engineered ricin toxin, then injected with ricin. They did not become ill
and suffered no apparent side effects, Vitetta reported. Next they will make
a ricin aerosol and test the mice, she said.
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-- Albert Einstein, letter to a friend, 1901
"I know of no safe depository of the ultimate powers of the society but the people themselves, and if we think them not enlightened enough to exercise control with a wholesome discretion, the remedy is not to take it from them, but to inform their discretion by education."
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