The World Health Organization (WHO) and U.S. Centers for Disease Control and 
Prevention (CDC) have labeled botulinum toxins as a high priority biological 
agent that may be used in terrorist attacks against food supplies. Due to this 
threat there is an increased need to develop fast and effective methods to 
detect active botulinum neurotoxins (BoNTs). This study reports the successful 
use of an enzymatic assay employing an internally quenched fluorogenic peptide 
as a fast, simple and inexpensive alternative to the mouse bioassay. In less 
than 15 min the assay can detect 0.25 nM BoNT-A in liquid food samples. The 
detection level is far below the adult human lethal oral dose of 70 microg of 
toxin. Immunomagnetic beads coated with IgG monoclonal antibodies that target 
the toxin heavy chain can concentrate the toxin without neutralizing its 
enzymatic activity, overcoming matrix effects caused by endogenous protease 
inhibitors and peptidases. This fast and effective assay system could be used 
for large scale screening to detect BoNT-A.