A sensitive cell-based assay for testing potency of botulinum neurotoxin type A

Area of Science:

• Neuroscience
• Biotechnology
• Toxicology

Background:

• Botulinum neurotoxin type A (BoNT/A) is a crucial biopharmaceutical for treating neurological disorders and in aesthetic medicine.
• The current standard for BoNT/A testing, the mouse bioassay (MBA), involves significant animal suffering and ethical concerns.
• There is an urgent need for non-animal alternatives that accurately assess BoNT/A activity.

Purpose of the Study:

• To develop and validate a sensitive, non-animal cell-based assay (CBA) for quantifying Botulinum neurotoxin type A (BoNT/A).
• To engineer a human neuroblastoma cell line for robust BoNT/A detection, replacing the traditional mouse bioassay (MBA).

Main Methods:

• Engineered LAN5 human neuroblastoma cells to express a NanoLuciferase-tagged SNAP25 reporter.
• Developed a quantitative luminometry assay to measure the NanoLuc-SNAP25 fragment released upon BoNT/A cleavage.
• Validated the assay's sensitivity using purified BoNT/A and a commercial BoNT/A product.

Main Results:

• The novel CBA demonstrated high sensitivity, detecting BoNT/A in the femtomolar (fM) range, comparable to the mouse bioassay (MBA).
• The assay successfully quantified BoNT/A activity from both purified toxin and a commercial product.
• The engineered LAN5 cells proved effective in replicating key steps of BoNT/A intoxication.

Conclusions:

• The developed cell-based assay offers a viable and sensitive alternative to the mouse bioassay for BoNT/A potency testing.
• This assay has the potential to significantly improve animal welfare in BoNT/A research and commercial applications.
• The assay supports scientific advancement by providing a reliable method for BoNT/A characterization.