title: Assignment of Opsonic Values to Pneumococcal Reference Serum 007sp for Use in Opsonophagocytic Assays for 13 Serotypes.
abstract: Opsonophagocytic assays (OPAs) are routinely used for assessing the immunogenicity of pneumococcal vaccines, with OPA data often being utilized for licensure of new vaccine formulations. However, no reference serum for pneumococcal OPAs is available, making evaluation of data among different laboratories difficult. This international collaboration was initiated to (i) assign consensus opsonic indexes (OIs) to FDA pneumococcal reference serum lot 007sp (here referred to as 007sp) and a panel of serum samples used for calibration of the OPA and (ii) determine if the normalization of the OPA results obtained with test samples to those obtained with 007sp decreases the variability in OPA results among laboratories. To meet these goals, six participating laboratories tested a panel of serum samples in five runs for 13 serotypes. For each serum sample, consensus OIs were obtained using a mixed-effects analysis of variance model. For the calibration serum samples, normalized consensus values were also determined on the basis of the results obtained with 007sp. For each serotype, the overall reduction in interlaboratory variability was calculated by comparing the coefficients of variation of the unadjusted and the normalized values. Normalization of the results substantially reduced the interlaboratory variability, ranging from a 15% reduction in variability for serotype 9V to a 64% reduction for serotype 7F. Normalization also increased the proportion of data within 2-fold of the consensus value from approximately 70% (average for all serotypes) to >90%. On the basis of the data obtained in this study, pneumococcal reference standard lot 007sp will likely be a useful reagent for the normalization of pneumococcal OPA results from different laboratories. The data also support the use of the 16 FDA serum samples used for calibration of the OPA as part of the initial evaluation of new assays or periodic assessment of established assays.
authors.affiliation: Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Burton
authors.affiliation: Department of Biometrics Research, Merck & Co., Inc., West Point, Pennsylvania, USA.
authors.forename: J
authors.initials: J
authors.lastname: Antonello
authors.affiliation: Pfizer Vaccine Research, Pfizer, Pearl River, New York, USA.
authors.forename: D
authors.initials: D
authors.lastname: Cooper
authors.affiliation: UCL Institute of Child Health, London, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Goldblatt
authors.affiliation: Department of Pediatrics and Center for Vaccine Evaluation and Study, Ewha Womans University School of Medicine, Seoul, South Korea.
authors.forename: K H
authors.initials: KH
authors.lastname: Kim
authors.affiliation: BioStat Consulting, LLC, Atlanta, Georgia, USA.
authors.forename: B D
authors.initials: BD
authors.lastname: Plikaytis
authors.affiliation: UCL Institute of Child Health, London, United Kingdom.
authors.forename: L
authors.initials: L
authors.lastname: Roalfe
authors.affiliation: GSK Vaccines, Rixensart, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Wauters
authors.affiliation: FDA/CBER, Silver Spring, Maryland, USA.
authors.forename: F
authors.initials: F
authors.lastname: Williams
authors.affiliation: Lanzhou Institute of Biological Products, Lanzhou, China.
authors.forename: G L
authors.initials: GL
authors.lastname: Xie
authors.affiliation: Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA mnahm@uabmc.edu Mustafa.Akkoyunlu@fda.hhs.gov.
authors.forename: M H
authors.initials: MH
authors.lastname: Nahm
authors.affiliation: FDA/CBER, Silver Spring, Maryland, USA mnahm@uabmc.edu Mustafa.Akkoyunlu@fda.hhs.gov.
authors.forename: M
authors.initials: M
authors.lastname: Akkoyunlu
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood*; D002138:Calibration; D007118:Immunoassay / Q000379:methods* / Q000592:standards*; D009895:Opsonin Proteins / Q000097:blood*; D010586:Phagocytes; D022242:Pneumococcal Vaccines / Q000276:immunology*; D012015:Reference Standards; D015203:Reproducibility of Results; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D009895:Opsonin Proteins; D022242:Pneumococcal Vaccines
keywords: 007sp; OPA; opsonic; pneumococcus; standardization