Portable bioluminescence test for botulinum neurotoxin

Botulism is a potentially fatal paralysis caused by botulinum neurotoxin (BoNT) which blocks neurotransmitter release. The family of eight BoNT serotypes are the most toxic naturally occurring substances known. In very small quantities, botulinum toxins can be used therapeutically to prevent muscle spasms and are increasingly available as licensed drugs for the treatment of a variety of disorders. Before they can be used in humans, each batch of BoNT is tested for safety, potency and stability, because the toxin is a biological product with inherent variability.

Worldwide, the most commonly used test is the mouse lethal dose 50 (LD50) assay. In this assay, mice are injected with a solution that is suspected to contain BoNT to determine the dose that will kill half of the animals at a defined time-point. The test causes severe suffering with observation of symptoms such as laboured breathing, weakness of limbs, and finally death due to asphyxiation. In the UK, around 70,000 mice are used each year for BoNT testing; globally the figure is estimated to be more than 600,000.  To overcome these limitations, in vitro BoNT assays have been developed, but these are limited because they fail to mimic all of the mechanisms that contribute to the toxin’s action in vivo.

The team at University of Freiburg led by Dr Gregory Stevens, has developed a novel automated bioluminescence assay for detecting BoNT (BLD-Test) which could replace the mouse bioassay. The assay can detect and distinguish all of the disease-causing BoNT serotypes, making the BLD-Test useful for analysis of samples from human and animal, foodstuff and environmental samples. The BLD-Test detects only active toxin, avoiding potential false positives caused by inactive BoNT, and can detect toxins in complex matrices.

Through CRACK IT Solutions Dr Stevens is currently working with multiple European partners ranging from academics, small companies and government organisations on a project to validate the BLD-Test so that it may be successfully adapted and developed to replace the mouse bioassay. This study will characterise, validate and document the performance of the bioassay so that users and regulators can have a high level of confidence in the ability of the BLD-Test to distinguish and detect different concentrations of BoNT in complex biological matrices.

Full details about this CRACK IT Solution and the outputs of the funded project can be found on the CRACK IT website.