Sensitive detection of botulinum neurotoxin type A using high-affinity polyclonal antibodies

Purpose of Study: The purpose of this study was to determine if a polyclonal antibody directed towards the heavy chain of botulinum toxin type A (BoNT/A) could be used to capture BoNT/A from complex matrices. Methods Used: Magnetic beads coated with a polyclonal antibody specific for BoNT/A heavy chain, List Prod #730, were used to capture and concentrate the toxin prior to addition of the substrate, FRET peptide SNAPtide®, List Prod #520. Various buffer conditions were tested to optimize the capture of toxin by the antibody. Generation of cleaved peptide was monitored using reverse phase HPLC with a fluorescence detector. Summary of Results: Initial studies indicated that as low as 1 pg of BoNT/A can be captured and detected using SNAPtide® in an overnight digestion at room temperature. Optimization of this assay is currently in progress. Conclusions: This highly sensitive assay captures and detects as low as 1 pg of BoNT/A which is significantly lower than one mouse LD50 (5 pg) and is in the equivalent range that can be detected by the gold standard mouse bioassay.