title: Results of an international transferability study of the BINACLE (binding and cleavage) assay for in vitro detection of tetanus toxicity.
abstract: 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. In line with the "3R" principles of replacing, reducing and refining animal tests, the "binding and cleavage" (BINACLE) assay for detection of active tetanus neurotoxin has been developed as a potential alternative to toxicity testing in animals. This in vitro test system can discriminate well between toxic and detoxified toxin molecules based on their receptor-binding and proteolytic characteristics. Here we describe an international study to assess the transferability of the BINACLE assay. We show that all participating laboratories were able to successfully perform the assay. Generally, assay variability was within an acceptable range. A toxin concentration-dependent increase of assay signals was observed in all tests. Furthermore, participants were able to detect low tetanus neurotoxin concentrations close to the estimated in vivo detection limit. In conclusion, the data from this study indicate that the methodology of the BINACLE assay seems to be robust, reproducible and easily transferable between laboratories. These findings substantiate our notion that the method can be suitable for the routine testing of tetanus toxoids.
authors.affiliation: Paul-Ehrlich-Institut (Federal Institute for Vaccines and Biomedicines), Paul-Ehrlich-Strasse 51-59, 63225 Langen, Germany. Electronic address: Heike.Behrensdorf@pei.de.
authors.forename: Heike A
authors.initials: HA
authors.lastname: Behrensdorf-Nicol
authors.affiliation: Paul-Ehrlich-Institut (Federal Institute for Vaccines and Biomedicines), Paul-Ehrlich-Strasse 51-59, 63225 Langen, Germany.
authors.forename: Ursula
authors.initials: U
authors.lastname: Bonifas
authors.affiliation: Health Canada, Centre for Vaccine Evaluation, 100 Eglantine Driveway, Ottawa, Ontario K1A 0K9, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Isbrucker
authors.affiliation: Institute of Virology and Immunology (IVI), Sensemattstrasse 293, 3147 Mittelhaeusern, Switzerland.
authors.forename: Hanspeter
authors.initials: H
authors.lastname: Ottiger
authors.affiliation: Division of Bacteriology, National Institute for Biological Standards and Control, MHRA, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Tierney
authors.affiliation: Paul-Ehrlich-Institut (Federal Institute for Vaccines and Biomedicines), Paul-Ehrlich-Strasse 51-59, 63225 Langen, Germany.
authors.forename: Kay-Martin
authors.initials: KM
authors.lastname: Hanschmann
authors.affiliation: Paul-Ehrlich-Institut (Federal Institute for Vaccines and Biomedicines), Paul-Ehrlich-Strasse 51-59, 63225 Langen, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Weisser
authors.affiliation: Paul-Ehrlich-Institut (Federal Institute for Vaccines and Biomedicines), Paul-Ehrlich-Strasse 51-59, 63225 Langen, Germany.
authors.forename: Beate
authors.initials: B
authors.lastname: Krämer
mesh_terms: D000818:Animals; D005240:Feasibility Studies; D006168:Guinea Pigs; D038622:Internationality; D059021:Laboratory Proficiency Testing; D057230:Limit of Detection; D011485:Protein Binding; D059748:Proteolysis; D015203:Reproducibility of Results; D018581:Technology Transfer; D013744:Tetanus Toxin / Q000302:isolation & purification / Q000378:metabolism; D013745:Tetanus Toxoid / Q000378:metabolism / Q000592:standards / Q000633:toxicity*; D018675:Toxicity Tests / Q000379:methods / Q000592:standards*
chemical_list: D013744:Tetanus Toxin; D013745:Tetanus Toxoid
keywords: In vitro toxicity assay; Tetanus neurotoxin; Toxoid vaccines; Transferability study