title: Reproducibility of serology assays for pandemic influenza H1N1: collaborative study to evaluate a candidate WHO International Standard.
abstract: Haemagglutination-inhibition (HI) and virus neutralisation (VN) assays are used to evaluate immunogenicity of pandemic H1N1 vaccines; however these bioassays are poorly standardised leading to inter-laboratory variation. A candidate International Standard (IS) for antibody to H1N1 pdm virus (09/194) was prepared from pooled sera of subjects who had either recovered from H1N1 pdm infection or who had been immunised with an adjuvanted subunit vaccine prepared from reassortant virus NYMC X-179A (derived from A/California/7/2009 virus). Ten laboratories from seven countries tested the candidate IS, 09/194 and a panel of human sera by HI and VN using the A/California/7/2009 virus (six laboratories) and/or the reassortant virus NYMC X-179A (ten laboratories). As expected, the inter-laboratory variability for HI and VN assay results was high. For results of antibody tests to NYMC X-179A, the % geometric coefficient of variation (%GCV) for 09/194 between laboratories was 83% for HI and 192% for VN. For tests of all sera, the median %GCV ranged from 95 to 345% for HI (80-fold variation) and 204 to 383% for VN (109-fold variation), but for the titres relative to 09/194 the median %GCV was much reduced (HI 34-231%; VN 44-214%). For tests of antibody to the A/California/7/2009 wild type virus there were similar reductions in %GCV when 09/194 was used. These results suggest that 09/194 will be of use to standardise assays of antibody to A/California/7/2009 vaccine and 09/194 has now been established by WHO as an IS for antibody to A/California/7/2009 with an assigned potency of 1300 IU per ml.
authors.affiliation: National Institute for Biological Standards and Control, Health Protection Agency, Potters Bar, United Kingdom.
authors.forename: John M
authors.initials: JM
authors.lastname: Wood
authors.forename: Diane
authors.initials: D
authors.lastname: Major
authors.forename: Alan
authors.initials: A
authors.lastname: Heath
authors.forename: Robert W
authors.initials: RW
authors.lastname: Newman
authors.forename: Katja
authors.initials: K
authors.lastname: Höschler
authors.forename: Iain
authors.initials: I
authors.lastname: Stephenson
authors.forename: Tristan
authors.initials: T
authors.lastname: Clark
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Katz
authors.forename: Maria C
authors.initials: MC
authors.lastname: Zambon
mesh_terms: D000914:Antibodies, Viral / Q000097:blood*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology* / Q000592:standards*; D007391:International Cooperation; D012015:Reference Standards; D015203:Reproducibility of Results; D012698:Serologic Tests / Q000379:methods / Q000592:standards; D014944:World Health Organization
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines