Patent ID: 8198034

Claim:
A method of quantifying botulinum neurotoxin serotype A (BoNT/A) activity in a sample, the method comprising the steps of: a. contacting a cell from an established cell line expressing a SNAP-25 polypeptide consisting essentially of at least a portion of human SNAP-25 comprising SEQ ID NO: 5 cleavable by BoNT/A with a sample comprising BoNT/A or suspected of comprising BoNT/A, wherein the established cell line is susceptible to BoNT/A intoxication at about or less than 500 pmol BoNT/A per liter culture medium, as indicated by the enzymatic cleavage of said SNAP-25 polypeptide by BoNT/A to yield a fragment of said SNAP25 polypeptide comprising the C-terminal amino acid sequence of SEQ ID NO: 38; b. isolating polypeptides from the cell; c. contacting the polypeptides with a monoclonal antibody comprising a heavy chain variable region comprising complementarity determining regions (CDRs) comprising the amino acid sequences of SEQ ID NOs: 95, 99, and 101 and a light chain variable region comprising CDRs comprising the amino acid sequences of SEQ ID NOs: 103, 108, and 113 that specifically binds to a fragment of said SNAP-25 polypeptide comprising the C-terminal amino acid sequence of SEQ ID NO: 38, wherein said antibody binds an epitope of said fragment comprising the carboxylated carboxyl-terminal glutamine with an equilibrium disassociation constant of less than 0.450 nM and wherein said antibody has an association rate constant for an epitope of intact SNAP-25 polypeptide comprising SEQ ID NO: 5 of less than 1×10 1 M −1 s −1 ; d. detecting the presence of any antibody-antigen complex comprising the antibody and the fragment of said SNAP25 comprising the C-terminal amino acid sequence of SEQ ID NO: 38; and e. quantifying the level of BoNT/A activity in the sample, wherein the higher the amount of the antibody-antigen complex detected the higher the level of BoNT/A activity in the sample.