Establishment of the First International Standard for Nucleic Acid Amplification Technology (NAT) Assays for HCV RNA


  • J. Saldanha,

    1. Division of Virology, National Institute for Biological Standards and Control, South Mimms, UK
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  • N. Lelie,

    1. Central Laboratory of The Netherlands Blood Transfusion Service, Amsterdam, The Netherlands
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  • A. Heath,

    1. Informatics Division, National Institute for Biological Standards and Control, South Mimms, UK
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  • WHO Collaborative Study Group

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    • 1 Members of the WHO Collaborative Study Group: Mr. Cleland/Dr. Davidson, University of Edinburgh, Edinburgh, UK; Drs. Conrad/Russell, National Genetics Institute, Los Angeles, USA; Dr. Cuypers, Central Laboratory of TheNetherlands Blood Transfusion Service, Amsterdam, The Netherlands; Dr. Fang, CSL Bioplasma, Victoria, Australia; Dr. Garson/Mr. Grant, University College London Medical School, London, UK; Prof. Gerlich, Institute of Medical Virology, Giessen, Germany; Drs. Giachetti/Mimms, Gen-Probe, San Diego, USA; Dr. Gröner, Centeon Pharma GmbH, Maburg, Germany: Dr. Hämmerle, Immuno AG, Orth, Austria; Dr. Kaiser, Institute for Medical Microbiology and Immunology, Bonn, Germany; Drs. Masecar/Savage, Bayer Corporation, Clayton, USA; Dr. Marissens, Hospital Universitaire St. Pierre, Brussels, Belgium; Dr. Nübling, Paul Ehrlich Institut, Langen, Germany; Drs. Pisani/Gentili, Istituto Superiore di Sanita, Rome, Italy; Dr. Sugata, St. Marianna University, Kanagawa, Japan; Drs. Vogel/Weimer, Centeon Pharma GmbH, Marburg, Germany; Dr. Widell, Malmö University Hospital, Malmö, Sweden; Drs. Wilber/Madej, Chjiron Corporation, Emeryville, USA; Dr. York, University of Natal, Natal, South Africa; Drs. Yu/Guo, CBER/FDA, Bethesda, USA; Dr. Zerlauth, Immuno AG, Vienna, Austria.

J. Saldanha, Division of Virology, National Institute for Biological Standards and Control, Blanche Lane, South Mimms, EN6 3QG (UK), Tel. +44 1707 654 753, Fax +44 1707 646 730, E-Mail


Background and Objectives: The aims of this study were the establishment of a WHO International standard for HCV RNA for nucleic acid amplification technology (NAT) assays and the determination of the HCV RNA content of the candidate standard. Materials and Methods: Twenty-two laboratories evaluated three candidate materials (two lyophilised, AA and BB, which were derived from the same source and one a liquid preparation, CC). All samples were HCV genotype 1 with a concentration of approximately 105 genome equivalents/ml. The methods used included the Roche Amplicor assay (version 1), Chiron Quantiplex (bDNA) assay, Organon Teknika NASBA assay, Transcription Mediated assay and various in-house assays, using single or nested primers. Results: There was reasonable agreement between the overall mean NAT detectable units/ml obtained by the different assays except for some of the in-house assays using single primers which gave substantially lower estimates. These titres were 5.0 log10 for samples AA and BB and 4.6 log10 for sample CC. Conclusions: Sample AA was accepted as the candidate standard and assigned a titre of 105 international units (IU)/ml. The International Standard consists of a batch of vials each containing 50,000 IU/vial. Preliminary studies indicated that the material is stable at +4°C and +20°C for up to 200 days.