Patent ID: 6962703

Claim:
A non-cytotoxic agent which specifically binds to a nociceptive afferent neuron, said agent comprising, a Targeting Moiety (TM) coupled to a modified clostridial neurotoxin in which the TM comprises a ligand that specifically binds to a cell-surface binding site present on a nociceptive afferent neuron, and the TM is capable of functionally interacting with a binding site causing a physical association between the agent and the surface of the nociceptive afferent neuron; wherein the clostridial neurotoxin heavy chain (H-chain) is removed or modified by chemical derivitisation, mutation or proteolysis to reduce or remove its native binding affinity for motor neurons; and the clostridial neurotoxin light chain (L-chain) or a fragment thereof retains a protease activity specific for components of the neurosecretory machinery; the TM and the modified H-chain, if present, forming a molecule which introduces the L-chain or fragment thereof into the cytosol of a nociceptive afferent neuron, thereby inhibiting the transmission of signals between a nociceptive afferent neuron and a projection neuron by controlling the release of at least one neurotransmitter or neuromodulator from the nociceptive afferent neuron.