title: Collaborative study for the calibration of a replacement international standard for diphtheria toxoid adsorbed.
abstract: We present the results of a collaborative study for the characterization of a preparation of diphtheria toxoid adsorbed, and its calibration in terms of the 3rd International Standard (IS) for Diphtheria Toxoid Adsorbed. Calibration was performed using established World Health Organization (WHO) and European Pharmacopoeia (Ph. Eur.) protection models. Two candidate toxoid preparations were included in the study, one of which was adopted as a replacement Ph. Eur. Biological Reference Preparation (BRP, batch 4) in February 2009. The second candidate preparation was found to have a unitage of 213 IU/ampoule based on the calibration by in vivo bioassay in 19 laboratories in 16 countries, and was established as the 4th IS for Diphtheria Toxoid Adsorbed by the WHO Expert Committee on Biological Standardization (ECBS) in October 2009. The study also assessed performance of the replacement standard in mouse and guinea pig serological assays which are used as alternative procedures for diphtheria potency testing. Participants tested both candidate preparations and potency was expressed in relative terms only. Results suggest that the replacement standard is suitable for use as the reference vaccine in serological assays and that the Vero cell assay may be suitable for calibration of future replacement standards.
authors.affiliation: Division of Bacteriology, National Institute for Biological Standards and Control, Health Protection Agency, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, United Kingdom. paul.stickings@nibsc.hpa.org.uk
authors.forename: Paul
authors.initials: P
authors.lastname: Stickings
authors.forename: Peter
authors.initials: P
authors.lastname: Rigsby
authors.forename: Laura
authors.initials: L
authors.lastname: Coombes
authors.forename: Kiran
authors.initials: K
authors.lastname: Malik
authors.forename: Paul
authors.initials: P
authors.lastname: Matejtschuk
authors.forename: Dorothea
authors.initials: D
authors.lastname: Sesardic
mesh_terms: D000327:Adsorption; D000818:Animals; D002138:Calibration; D002522:Chlorocebus aethiops; D003299:Cooperative Behavior; D004168:Diphtheria Toxoid / Q000493:pharmacokinetics / Q000592:standards*; D005260:Female; D006168:Guinea Pigs; D007391:International Cooperation; D007753:Laboratories / Q000592:standards; D008297:Male; D051379:Mice; D010602:Pharmacopoeias as Topic / Q000592:standards*; D012015:Reference Standards; D054928:Validation Studies as Topic; D014709:Vero Cells; D014944:World Health Organization
chemical_list: D004168:Diphtheria Toxoid