A system and method for identifying a botulinum neurotoxin inhibitor
employing a botulinum neurotoxin substrate complex having a peptide
substrate, preferably SNAP-25, a reporter domain on one side of said
peptide substrate and an immobilization domain on the opposite side of
said peptide substrate. The botulinum neurotoxin inhibitor is identified
by its ability to decrease the relative amount of cleaved complex,
detected through measuring a decrease in complex bound to a solid
support. The method of the present invention also utilizes novel cells
that express a botulinum neurotoxin substrate complex. The methods of the
present invention are adapted for cell based screening to monitor the
catalytic activity of a BoNT in living cells and to identify molecules
that inhibit the catalytic activity of a BoNT in living cells. Also
provided are novel stable cell lines that express the botulinum toxin
substrate complex and viral vectors capable of efficiently expressing an
active light chain of the BoNT within mammalian cells.