Transferability study of the BINACLE (binding and cleavage) assay for in vitro determination of botulinum neurotoxin activity.

The muscle-relaxing effects of the botulinum neurotoxin (BoNT) serotypes A and B are widely used in clinical and aesthetic medicine. The standard method for measuring the biological activity of pharmaceutical BoNT products is a mouse bioassay. In line with the European Directive 2010/63/EU, a replacement by an animal-free method would be desirable.

Is the test for irreversibility of tetanus toxoids still relevant?

Tetanus vaccines for human and veterinary use are based on toxoids resulting from a formaldehyde-mediated inactivation of tetanus neurotoxin (TeNT). Due to the high toxicity of TeNT, safety tests are mandatory for each batch of these toxoids. One of the tests addresses the irreversibility of inactivation: The toxoid is stored at 37 °C for 6 weeks and then subjected to in vivo toxicity testing.

In vitro potency determination of botulinum neurotoxin serotype A based on its receptor-binding and proteolytic characteristics.

Botulinum neurotoxins (BoNTs) inhibit the release of the neurotransmitter acetylcholine from motor neurons, resulting in highly effective muscle relaxation. In clinical and aesthetic medicine, serotype BoNT/A, which is most potent for humans, is widely used to treat a continuously increasing spectrum of disorders associated with muscle overactivity. Because of the high toxicity associated with BoNTs, it is mandatory to precisely determine the potency of every batch produced for pharmaceutical purposes.

In vitro potency determination of botulinum neurotoxin B based on its receptor-binding and proteolytic characteristics.

Botulinum neurotoxins (BoNTs) are the most potent toxins known. However, the paralytic effect caused by BoNT serotypes A and B is taken advantage of to treat different forms of dystonia and in cosmetic procedures. Due to the increasing areas of application, the demand for BoNTs A and B is rising steadily.

"BINACLE" assay for in vitro detection of active tetanus neurotoxin in toxoids.

Tetanus neurotoxin (TeNT) consists of two protein chains connected by a disulfide linkage: The heavy chain mediates the toxin binding and uptake by neurons, whereas the light chain cleaves synaptobrevin and thus blocks neurotransmitter release.Chemically inactivated TeNT (tetanus toxoid) is utilized for the production of tetanus vaccines. For safety reasons, each toxoid bulk has to be tested for the "absence of toxin and irreversibility of toxoid".

Results of an international transferability study of the BINACLE (binding and cleavage) assay for in vitro detection of tetanus toxicity.

Tetanus vaccines contain detoxified tetanus neurotoxin. In order to check for residual toxicity, the detoxified material (toxoid) has to be tested in guinea pigs. These tests are time-consuming and raise animal welfare issues.

Binding and cleavage (BINACLE) assay for the functional in vitro detection of tetanus toxin: applicability as alternative method for the safety testing of tetanus toxoids during vaccine production.

Tetanus toxoids (i.e. chemically inactivated preparations of tetanus neurotoxin) are used for the production of tetanus vaccines.

In vitro determination of tetanus toxicity by an endopeptidase assay linked to a ganglioside-binding step.

Assays for the detection of tetanus neurotoxin (TeNT) are relevant for research applications as well as for the safety testing of tetanus vaccines. So far, these assays are usually performed as toxicity tests in guinea pigs or mice. The alternative methods described to date were mostly based on the detection of the toxin's proteolytic activity.