1 / 20

Preparation, characterization and establishment of a WHO International Biological Reference Preparation

Preparation, characterization and establishment of a WHO International Biological Reference Preparation. Dr Sjoerd Rijpkema Division of Bacteriology NIBSC. How are International Standards prepared?. Experts select material that is suitable to serve as a standard for diagnostic assays

loyal
Télécharger la présentation

Preparation, characterization and establishment of a WHO International Biological Reference Preparation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Preparation, characterization and establishment of a WHO International Biological Reference Preparation Dr Sjoerd Rijpkema Division of Bacteriology NIBSC

  2. How are International Standards prepared? • Experts select material that is suitable to serve as a standard for diagnostic assays • Filled and freeze dried • Long term stability • Suitability for use is established in a collaborative study • Statistical analysis of raw assay data • Arbitrary unitage is assigned

  3. Reference panel for Chagas disease • Chagas disease is a global threat to public health • Antibody panel • Suitable for all diagnostic tests • Specific for Tc I and Tc II • Cross-reactive antibodies • Antibody titre range

  4. Source material • Represent geographic origins of disease • Informed consent/local ethical approval • Serum/Plasma/Recalcified plasma • Pooled samples or individual sample • Certified free of HIV1/2, HepA/B/C • Certified free of T. cruzi parasites • Source material ‘fit for purpose’ pre & post freeze drying • Pilot study FD conditions • ‘fit for purpose’ post freeze drying • 1000 – 5000 ampoules

  5. Aim of the collaborative study • Establish suitability of the candidate standard in a range of assays including the ‘gold’ standard • Collect international data set • Statistical analysis of raw data • Assign a unitage • Evaluate differences in assay methods • Evaluate inter-laboratory differences (GCV)

  6. Collaborative study design • Create project team • Select international participants • Represent reference and specialist diagnostic laboratories • Select samples for analysis pack • Select test or range of tests • Samples tested as part of routine • No re-imbursement for testing

  7. Project Team • Internal • Project leader • Statistician • Formulation scientist • Fill & freeze dry/packaging & distribution • External • Expert(s) • Specialist diagnostic laboratories • Participants of the collaborative study

  8. Collaborative study (1) • Participants • Global distribution • Duplicate sample packs distributed • Blinded samples • Candidate standard duplicated • Positive + Negative control samples • Tests • Selection agreed in the CS design • Carried out in duplicate on at least two separate days = 4 tests per sample

  9. Sample pack for the collaborative study of 05/122 & 05/132

  10. Collaborative study (2) • Collate raw test data • Calculate mean test value, CI and GCV • Accelerated degradation studies • Test stability of candidate standards stored at +37oC to –20oC • Draft report and propose unitage • Final report endorsed by all members of CS • Report send to WHO-ECBS for approval • Publish study

  11. Collection of raw data • Titration methods: yield endpoint titre • Each sample tested 4x on two separate days • 8 data points/sample • EIA Methods: produce a numerical value • Each sample tested in 4 sequential dilutions on two separate days • 8 data points/sample • In-house methods: standard procedures • Commercially available tests: manufacturer’s protocol

  12. Stability of biological standards • The stability of a biological standard is predicted by an accelerated thermal degradation test. • Samples of the standard are stored at elevated temperatures at 4oC to 56oC. • Storage time ranges from 6 months to 2 years. • The activity of these samples is then calculated relative to those samples stored at -20oC (T0).

  13. The method • Biological activity is assumed to degrade exponentially with time. This is a “first-order” process. • An estimate of k(T0) is required to predict the stability of the standard, but k(T) can only be estimated for T>T0.

  14. Arrhenius equation Log { k(T) } 1 / T 37oC 20oC 4oC -20oC • log{k(T)} is: • Linear with 1/T • log{k(T)} =  + /T • Independent of time

  15. Accelerated degradation • Predicts degradation process & rate

  16. Effect of accelerated degradation on potency of 05/122 and 05/132

  17. Timeline of a collaborative study • MTA agreed 1 mo • Source samples shipped +1 mo 2 mo • Pilot study freeze dry +2 mo 4 mo • Test FD samples +2 mo 6 mo • Fill and freeze dry +2 mo 8 mo • Ship sample packs +3 mo 11 mo • Collect results +3 mo 14 mo • Analyse data +3 mo 17 mo • Submit report • Approval by WHO ECBS 2011? • Publication

  18. Biological standards produced by NIBSC meet WHO criteria • ISO 9001 and ISO 13485 • All containers in the batch are identical • Potency is unchanged after processing • Stable – indefinite shelf life • Low moisture content • Oxygen level (<1%) • Sterility testing: pre & post filling & freeze drying • Fill weight variation control • Full production records

  19. References • For a detailed description of the standard specification see: • WHO technical bulletin series 932. ISBN 92-4-120932-1 • http://www.who.int/biologicals/expert_committee/TRS932CVR%20with%20full%20Texts.pdf • For accelerated degradation see: • Kirkwood TBL. Predicting the stability of biological standards and products. Biometrics 1977; 33: 736-742. • Shin J, Nam J. Validation of a computer software program for statistical analysis of accelerated stability studies on biological standards. Biologicals 2007; 35: 27-30.

  20. Acknowledgements • Peter Rigsby, Statistical Division • Paul Matejtschuk, Centre for Biological Reference Materials

More Related