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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT OF DETECTION TECHNOLOGIES FOR TOXINS AND THEIR VALIDATION IN FOOD MATRICES Title: Immunochemical technologies for replacement of rodent bioassays in sensitive detection of toxins in foods

Authors
item Carter, John
item Cheng, Luisa Wai Wai
item He, Xiaohua
item Rasooly, Reuven
item Brandon, David
item Stanker, Larry

Research conducted cooperatively with:
item Safeguard Biosystems, Inc.

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 1, 2008
Publication Date: February 25, 2010
Citation: Carter, J.M., Cheng, L.W., He, X., Rasooly, R., Brandon, D.L., Stanker, L.H. 2010. Immunochemical technologies for replacement of rodent bioassays in sensitive detection of toxins in foods. Proceedings from Biodetection Technologies 6th Edition. 5:75-95.

Technical Abstract: Rapid sensitive assays for biothreat toxins that can be used to detect intentionally contaminated foods are now typically performed via bioassay in live mice. While bioassay provides essential data on bioavailability, animal models are technically, fiscally, and ethically challenging. Through careful application of state-of-the-art techniques for immunization and screening, we created new monoclonal antibody reagents (MAb) specific for detection of botulinum neurotoxin (BoNT). These MAbs bind BoNT so tightly that, in a sandwich ELISA, they are more sensitive than the rodent bioassay. These reagents are also useful for sample preparation and production of portable tests for field use. Through a CRADA with Safeguard Biosystems Corp., we used these MAbs to develop a simple “dipstick” assay that can detect BoNT in food at levels well below the human oral LD50. We also used the new MAbs to develop sample preparation methods based on immunomagnetic beads. In liquefied food extracts these beads rapidly and irreversibly bind all toxin present in a large sample. Sequestering the beads with a magnet effectively concentrates the toxin into a small volume suitable for laboratory testing. While the toxin is still bound to the beads, we can detect its highly specific peptidase activity using a fluorescence (FRET) based substrate, for detection of sublethal amounts of BoNT in foods.

Last Modified: 4/18/2014
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