Reproducibility of Serologic Assays for Influenza Virus A (H5N1)

• DOI: 10.3201/eid1508.081754
• Publication Date: 2009-08-19T16:50:45Z
• Authors: Iain Stephenson; Alan Heath; Diane Major; Robert W. Newman; Katja Hoschler; Wang Junzi; Jacqueline M. Katz; Jerry P. Weir; Maria C. Zambon; John M. Wood
• Keywords: 0301 basic medicine; 572; Infectious and parasitic diseases; RC109-216; immunogenicity; Antibodies, Viral; World Health Organization; Communicable Diseases; Communicable Diseases, Emerging; Antibodies; 03 medical and health sciences; serologic assays; Neutralization Tests; vaccine; Influenza, Human; Influenza A Virus; Animals; Humans; viruses; False Positive Reactions; Serologic Tests; Viral; Emerging; Sheep; Influenza A Virus, H5N1 Subtype; pandemic; Research; R; Reproducibility of Results; Hemagglutination Inhibition Tests; Reference Standards; Influenza; 3. Good health; Influenza Vaccines; Medicine; H5N1 Subtype; influenza; Laboratories; Human

Hemagglutination-inhibition (HI) and neutralization are used to evaluate vaccines against influenza virus A (H5N1); however, poor standardization leads to interlaboratory variation of results. A candidate antibody standard (07/150) was prepared from pooled plasma of persons given clade 1 A/Vietnam/1194/2004 vaccine. To test human and sheep antiserum, 15 laboratories used HI and neutralization and reassortant A/Vietnam/1194/2004, A/turkey/Turkey/1/2005 (clade 2.2), and A/Anhui/1/2005 (clade 2.3.4) viruses. Interlaboratory variation was observed for both assays, but when titers were expressed relative to 07/150, overall percentage geometric coefficient of variation for A/Vietnam/1194/2004 was reduced from 125% to 61% for HI and from 183% to 81% for neutralization. Lack of reduced variability to clade 2 antigens suggested the need for clade-specific standards. Sheep antiserum as a standard did not reliably reduce variability. The World Health Organization has established 07/150 as an international standard for antibody to clade 1 subtype H5 and has an assigned potency of 1,000 IU/ampoule.