Reproducibility of serologic assays for influenza virus A (H5N1).
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.
Stephenson
Iain
I
University of Leicester, UK. iain.stephenson@uhl-tr.nhs.uk
Heath
Alan
A
Major
Diane
D
Newman
Robert W
RW
Hoschler
Katja
K
Junzi
Wang
W
Katz
Jacqueline M
JM
Weir
Jerry P
JP
Zambon
Maria C
MC
Wood
John M
JM
D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis / Q000097:blood; D021821:Communicable Diseases, Emerging / Q000276:immunology / Q000517:prevention & control / Q000821:virology; D005189:False Positive Reactions; D006385:Hemagglutination Inhibition Tests / Q000379:methods / Q000706:statistics & numerical data; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000235:genetics / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology* / Q000592:standards*; D007251:Influenza, Human / Q000276:immunology / Q000517:prevention & control / Q000821:virology; D007753:Laboratories; D009500:Neutralization Tests / Q000379:methods / Q000706:statistics & numerical data; D012015:Reference Standards; D015203:Reproducibility of Results; D012698:Serologic Tests / Q000379:methods* / Q000706:statistics & numerical data; D012756:Sheep; D014944:World Health Organization
D000914:Antibodies, Viral; D007252:Influenza Vaccines