ARS | Publication request: Immunochemical technologies for replacement of rodent bioassays in sensitive detection of toxins in foods

Submitted to: Meeting Abstract
Publication Type: Abstract
Publication Acceptance Date: October 1, 2008
Publication Date: N/A
Publisher's URL: http://knowledgefoundation.com

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.