title: Collaborative study for the calibration of a replacement International Standard for Tetanus Toxoid Adsorbed.
abstract: We present the results of a collaborative study for the establishment of a replacement International Standard (IS) for Tetanus Toxoid Adsorbed. Two candidate preparations were included in the study, one of which was established as the 4th IS for Tetanus Toxoid Adsorbed at the WHO Expert Committee on Biological Standardization meeting in October 2010. This preparation was found to have a unitage of 490 IU/ampoule, based on calibration in guinea pig challenge assays. Results from mouse challenge assays suggest that the relative performance of two candidate preparations may differ significantly between guinea pigs and mice. The authors note that the number of laboratories that performed guinea pig challenge assays, which are used to calibrate and assign IU, is much lower than in previous collaborative studies and this may have implications for calibration of replacement standards in the future. The issue of assigning separate units to the IS for guinea pig and mouse assays is discussed. The study also assessed performance of the replacement standard in serological assays which are used as alternative procedures to challenge assays for tetanus potency testing. Results suggest that the replacement standard is suitable for use as the reference vaccine in serological assays.
authors: Division of Bacteriology, National Institute for Biological Standards and Control, Health Protection Agency, Blanche Lane, South Mimms, Potters Bar, Hertfordshire, United Kingdom. rob.tierney@nibsc.hpa.org.uk
authors: Rob
authors: R
authors: Tierney
authors: Paul
authors: P
authors: Stickings
authors: Jason
authors: J
authors: Hockley
authors: Peter
authors: P
authors: Rigsby
authors: Masaaki
authors: M
authors: Iwaki
authors: Dorothea
authors: D
authors: Sesardic
mesh_terms: D000327:Adsorption; D000818:Animals; D001681:Biological Assay / Q000379:methods / Q000592:standards*; D002138:Calibration; D006168:Guinea Pigs; D007391:International Cooperation; D007753:Laboratories / Q000592:standards*; D051379:Mice; D012015:Reference Standards; D015203:Reproducibility of Results; D013045:Species Specificity; D013745:Tetanus Toxoid / Q000276:immunology / Q000493:pharmacokinetics / Q000592:standards*
chemical_list: D013745:Tetanus Toxoid