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biodefense

Heptavalent Botulinum Toxin Vaccine

"U.S. may have answer to feared bioweapon"
By Pamela Hess
Pentagon correspondent


Washington, DC, Mar. 1 (UPI) -- The U.S. government is funding a new British vaccine technology that could neutralize one of the most feared biological weapons, botulinum neurotoxin.


Just two years ago on the eve of war with Iraq, a U.S. Army medical official told reporters there was serious concern about the use of botulinum toxin against U.S. troops. It was perhaps the most feared threat because there was no single vaccine to battle it, and treating botulinum poisoning on the battlefield would be exceptionally difficult.

This week, the U.S. government awarded a $3.5 million grant to Cambridge BioStability Limited, in Cambridge, U.K., to combine newly developed vaccines for all seven kinds of botulinum toxin into a single, stable inoculation.

Currently, the seven serotypes of botulinum require different shots to cover each toxin, with three shots in each course.

The National Institute of Allergy and Infectious Diseases in Bethesda, Md., has developed the vaccines, which are toxoids -- non-poisonous cousins of the toxins that elicit the body's immune response.

Cambridge has developed a technology of drying and storing each of the separate vaccines in glass microspheres and suspending them in a neutral liquid that allows them to be held for long periods without refrigeration. It also allows a single shot to deliver protection for all seven versions of the poison, according to Bruce Roser, chief scientific adviser for Cambridge. Unless they are sequestered, the vaccines will harm each other.

"This is the first time that all seven serotypes could be combined in a stable single dose," Roser told United Press International.

The technology is derived from a natural phenomenon called anhydrobiosis, according to Roser. Some creatures and plants can survive for hundreds of years in a dessicated state. They produce a sugar substance to replace their bodily fluids. As water is exuded, the sugar hardens to a glass-like structure. If water is added later, the organism returns to life.

The shot technology works in the same way. Cambridge first sprays the vaccine with a sugar solution, which dries the toxoid and encases it in the microscopic non-crystalline glass spheres. The spheres are suspended in an inert liquid, and when injected into the muscle the body's fluids break down the glass and release the vaccine.

Roser said Cambridge is developing a possible time-release mechanism that would prevent the need for booster shots for the immunization, which now requires three inoculations to be effective.

If deliberately released and inhaled, botulinum neurotoxin affects the body within hours, causing paralysis or death. The paralysis can last for months, during which the victim cannot breathe without a respirator. Tetanus once caused similar symptoms, but the disease can be neutralized by a vaccine that also is suspended in a stable liquid. Hepatitis B vaccine is similarly packaged.

The commander of the Army Medical Research Institute for Infectious Diseases in Frederick, Md., told reporters in January 2003 that botulinum toxin topped his list of concerns in the event of an Iraq war.

"That's a ... threat that I wish we had more in our medical toolbox for," said Col. Erik Henchal.

The CIA told Congress in 1996 that Iraq was thought to have produced at least 33 pounds to 44 pounds of dried botulinum toxin, which is also the main ingredient for Botox, the popular cosmetic treatment.

USAMRIID has developed a stable of seven vaccines to counter the seven varieties of BT, but Henchal said the organization has had a difficult time getting the vaccine into production so it can be delivered in a useable form.

Under this new arrangement, NIAID produces the genetically engineered toxin light chains, while Cambridge stabilizes them in an injectable liquid. Battelle Laboratories in Columbus, Ohio, is conducting the preliminary testing in animals.

Another firm, DynPort Vaccine Company LLC, also in Frederick, Md., is coordinating the project with a $5.4 million overall contract, Roser said.

"Since we are using our well established and simple methods to stabilize the toxins, we can do our part of the whole project quite cheaply and quickly," Roser said. "We estimate (the production of the serum will take) three years, but that is because the production of all seven recombinant serotypes will take that long. Our stabilization process could move much quicker with the right resources."

The right resources are vast, however. Roser told UPI the $3.5 million will allow the vaccine to be developed, but to produce it in useful numbers will take "several hundred million dollars."

He said Cambridge plans to make the vaccine technology available to the U.S. government, so it can begin stockpiling other stable vaccines in mass quantities at room temperature.
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