Comparison between a new multiplex electrochemiluminescence assay and the WHO reference enzyme-linked immunosorbent assay to measure serum antibodies against pneumococcal serotype-specific polysaccharides |
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Authors: | Muriel Feyssaguet,Aurélie Bellanger,Florence Nozay,Damien Friel,Estelle Merck,Vincent Verlant,Michel Malevé,Stéphane Lallemand,Abdelkarim El Moussaoui,Polly De Gorguette D Argoeuves,Tessa Jones,David Goldblatt,Sonia Schoonbroodt |
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Affiliation: | 1. GSK, Rue de l''Institut 89, 1330 Rixensart, Belgium;2. GSK, Avenue Fleming 20, 1300 Wavre, Belgium;3. UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London WC1N 1EH, United Kingdom |
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Abstract: | BackgroundTwo electrochemiluminescence (ECL) assays were developed which, together, can simultaneously measure serum antibodies against pneumococcal capsular polysaccharides (PnPS) for 17 serotypes. The assays were validated for the 13 PnPS included in the 13-valent pneumococcal conjugate vaccine (PCV13). As recommended by the World Health Organization (WHO), we compared the ECL assays with the WHO reference enzyme-linked immunosorbent assay (ELISA) and derived a threshold corresponding to the 0.35?µg/mL threshold established for the WHO reference ELISA for the non-inferiority comparison and licensure of new PCVs against invasive pneumococcal disease.MethodsA panel of 452 serum samples from children vaccinated with one of the three licensed PCVs was assessed with the ECL assays and the WHO reference ELISA. The ECL assay threshold for the aggregated seven PnPS included in the 7-valent PCV (PCV7) and serotype-specific thresholds were determined using a receiver operating characteristics (ROC) curve-based approach and Deming regression. To evaluate concordance between the ECL assays and the WHO reference ELISA, serostatus agreement rates between both assays and geometric means of the ratios (GMRs) of concentrations obtained with both assays were calculated.ResultsThe thresholds for the seven aggregated PCV7 serotypes obtained with the ROC curve-based approach and Deming regression approximated 0.35?µg/mL (0.38 and 0.34?µg/mL, respectively). Individual thresholds for the PCV13 serotypes ranged between 0.24 and 0.51?µg/mL across both approaches. Serostatus agreement rates using a 0.35?µg/mL threshold for both assays were ≥86.9% for all PCV13 serotypes. GMRs ranged between 0.85 and 1.25 for 11/13 serotypes and were <1.29 for the two remaining serotypes.ConclusionThe ECL assays were comparable to the WHO reference ELISA and offer a sensitive, time- and serum volume-saving method to quantify serotype-specific anti-PnPS antibodies in pediatric sera. A 0.35?µg/mL threshold will be used for each PCV13 serotype to assess PCV immunogenicity in clinical trials. |
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Keywords: | BSA bovine serum albumin CI confidence interval CWPS multi pneumococcal cell wall polysaccharide multi DPBS Dulbecco’s phosphate buffered saline DPBST Dulbecco’s phosphate buffered saline containing 0.05% Tween-20 ECL electrochemiluminescence ELISA enzyme-linked immunosorbent assay GMR geometric mean of the ratios ICH Institute of Child Health IgG immunoglobulin G IPD invasive pneumococcal disease LLOQ lower limit of quantitation MSD Meso Scale Discovery PCV pneumococcal conjugate vaccine PCV13 13-valent pneumococcal conjugate vaccine PCV7 7-valent pneumococcal conjugate vaccine PCV9 9-valent pneumococcal conjugate vaccine PHiD-CV PnPS pneumococcal capsular polysaccharide RCDC reverse cumulative distribution curve ROC receiver operating characteristics ULOQ upper limit of quantitation WHO World Health Organization Electrochemiluminescence assay Enzyme-linked immunosorbent assay Pneumococcal polysaccharides Threshold Bridging Concordance |
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