Abstract
Botulinum toxin is an exceedingly potent inhibitor of neurotransmission across the neuromuscular junction, causing flaccid paralysis and death. The potential for misuse of this deadly poison as a bioweapon has added a greater urgency to the search for effective therapeutics. The development of sensitive and efficient cell-based assays for the evaluation of toxin antagonists is crucial to the rapid and successful identification of therapeutic compounds. The authors evaluated the sensitivity of primary cultures from 4 distinct regions of the embryonic chick nervous system to botulinum neurotoxin A (BoNT/A) cleavage of synaptosomal-associated protein of 25 kD (SNAP-25). Although differences in sensitivity were apparent, SNAP-25 cleavage was detectable in neuronal cells from each of the 4 regions within 3 h at BoNT/A concentrations of 1 nM or lower. Co-incubation of chick neurons with BoNT/A and toxin-neutralizing antibodies inhibited SNAP-25 cleavage, demonstrating the utility of these cultures for the assay of BoNT/A antagonists. (Journal of Biomolecular Screening 2007:370-377)