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Plants, Fabric Involved in Anti-Anthrax Research By Chris Schneidmiller WASHINGTON — The next breakthrough against an anthrax attack could be carried by tobacco plants or infused into soldiers’ clothing, scientists said this week during the 2005 Biodefense Research Meeting of the American Society for Microbiology (see GSN, Jan. 28). More than 200 research papers were presented at the four-day conference in Baltimore. While scientists continue to seek improved smallpox and anthrax vaccines, others are approaching the fight from different angles. Among the research subjects: detecting infection through use of light or breath checks, and a food preservative that neutralizes anthrax spores. “Were starting to see a lot of new technology at the very early stages,” said ASM spokesman Jim Sliwa. “It’s almost like we’re starting to see the fruits of the biodefense investment that was made several years ago” (see GSN, March 1). Scientists Les Baillie and Vidadi Yusibov have been working for two years to use tobacco plants to produce antibodies that could be used to protect humans from anthrax. The “plantibodies” are developed by collecting antibody-producing cells from people who have been vaccinated against the infection. Encoded genes are transferred into a plant, which begins producing antibodies in a matter of days. The entire process takes two to three months, said molecular biologist Yusibov, scientific director of the Fraunhofer USA Center for Molecular Biotechnology in Delaware. Tests on mice have shown the plantibodies produce full protection against anthrax spores, Yusibov said. “The antibodies we made in plants are just as good as the antibodies we made in humans,” he said. Tobacco plants were chosen for their large leaves, which able to carry higher numbers of antibodies, Yusibov said. Plants such as lettuce are also being considered for use. There are several benefits to using plants, the scientists said. Producing antibodies now requires large facilities that can cost hundreds of millions of dollars and take years to build, Yusibov said. Large numbers of tobacco plants could essentially be grown in greenhouses, removing up to 90 percent of the capital cost. The risk of contamination by other diseases in growing antibodies in human or mammal cells is also eliminated; plant viruses are not known to affect humans, said Baillie, a microbiologist at the University of Maryland Biotechnology Institute. Large numbers of antibodies could be extracted from the plants and stored for years in preparation for a possible attack. Unlike vaccines, which can take weeks to months to provide protection, the virus-disabling proteins go to work immediately. They can be used before exposure to block infection or as a treatment after infection. There is still an extensive amount of work to be done before the plant-produced antibodies could be ready for use, the scientists said. They are planning tests on rabbits and monkeys this year, which would be followed by safety testing on humans. The U.S. Food and Drug Administration must also approve use of the treatment. Questions on the antibody yield and efficacy from the plants also need to be answered, the scientists said. Baillie and Yusibov hope their research will assist efforts to defend both the U.S. military and civilian populations from an anthrax attack. Their work has received significant funding from the Defense Department, and has been championed by U.S. Senator Joseph Biden (D-Del.). They aren’t stopping with one bioagent, either: plantibodies against plague and botulism are also being developed. “The hope is that it will produce the capability for the Department of Defense and Department of Homeland Security to respond to a biological attack,” Baillie said. “We’re very hopeful this will come to something.” Robert Engel, a chemistry and biochemistry professor at Queens College in New York, hopes he has developed a treated fabric that will kill anthrax spores before they can infect the wearer. Engel and collaborators JaimeLee Cohen and Karin Melkonian have been working for three years to perfect a process by which an antimicrobial detergent could be chemically attached to fabric, wood, paper and other surfaces. The idea is to kill bacteria on contact with the surface, Engel said. “It’s like stabbing the bacteria,” he said. While it has potential commercial antibacterial and antifungal uses, it is the possible military application that has caught the attention of the U.S. Army Soldier Systems Center in Natick, Mass., which develops clothing, food, shelters and other requirements for soldiers. Microbiologist Jon Calomiris since last fall has been testing the feasibility of using treated fabric against anthrax. Tests at room temperature showed that 90 percent of dormant spores of a nonpathogenic strain of anthrax were killed within five hours of being applied directly to cloth samples treated with the detergent. The kill rate reached 99 percent within one hour at higher temperatures and humidity, while spores on nontreated control fabrics remained viable. Anthrax spores are hardest to kill during when dormant. Active spores would likely be easier to eliminate, as would other viruses or bacteria that might be used against soldiers, said Heidi Schreuder-Gibson, primary officer for the project at the Natick center. Testing indicates that using antimicrobial fabric is possible, said Calomiris, who works at the U.S. Air Force Research Laboratory at the Aberdeen Proving Ground in Maryland. Someday, the treatment might be used for clothing, tents or tarps to protect soldiers or “in any situation where there is a release of anthrax spores and there is concern about the spores settling on a fabric,” he said. Development is in the “very early” stages, Schreuder-Gibson said. Calomiris said he will spend several months performing tests using different treatments at different temperatures and humidity, and will test the fabric’s efficacy against aerosolized spores. Further research would be needed on the potential health effects of using the antimicrobial compound, and its potential application in the field. Schreuder-Gibson said she hopes to have prototype garments ready for testing under a range of conditions in 2007. “We’re only interested in compounds that would work under the toughest conditions,” she said.
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