J Korean Med Sci.  2018 Dec;33(51):e340. 10.3346/jkms.2018.33.e340.

Validation of a Multiplexed Opsonophagocytic Assay for 11 Additional Pneumococcal Serotypes and Its Application to Functional Antibody Evaluation Induced by Pneumococcal Polysaccharide Vaccine

• Cha J
• Kim HW
• Lee JH
• Lee S
• Kim KH

• KMID: 2428639
• DOI: http://doi.org/10.3346/jkms.2018.33.e340

Abstract

BACKGROUND
Various pneumococcal vaccines have been evaluated for immunogenicity by opsonophagocytic assay (OPA). A multiplexed OPA (MOPA) for 13 pneumococcal serotypes was developed by Nahm and Burton, and expanded to 26 serotypes in 2012. The development of new conjugate vaccines with increased valence has necessitated expanded MOPAs to include these additional serotypes. In this study, we validated this expanded MOPA platform and applied to measure antibodies against 11 additional serotypes (2, 8, 9N, 10A, 11A, 12F, 15B, 17F, 20B, 22F, and 33F) in human sera.
METHODS
All materials, including serum, complement, bacterial master stocks, and HL-60 cells, were evaluated for assay optimization. Following optimization, the assay was validated for accuracy, specificity, and intra- and inter-assay precision with sera from adult donors following standard protocols. The assay was applied to evaluate functional antibodies of 42 sera immunized with 23-valent pneumococcal polysaccharide vaccine (PPV23).
RESULTS
The expanded MOPA platform was specific for all serotypes, with the exception of serotype 20. The assay results were highly correlated with those obtained from single-serotype OPA, indicating acceptable accuracy. The coefficients of variation were 7%-24% and 13%-39% in tests of intra- and inter-assay precision, respectively, using three quality-control samples. A MOPA that included 11 additional serotypes in the PPV23 was established and validated with respect to accuracy, specificity, and precision. The opsonic indices of immune sera were obtained using this validated assay.
CONCLUSION
The expanded MOPA will be useful for evaluation of the immunogenicity of PPV23 and future conjugate vaccine formulations.

Keyword

Pneumococcal Vaccines; Immunogenicity; Opsonin Proteins; Biologic Assay; Validation Studies

MeSH Terms

Adult
Antibodies
Biological Assay
Complement System Proteins
HL-60 Cells
Humans
Immune Sera
Opsonin Proteins
Pneumococcal Vaccines*
Sensitivity and Specificity
Serogroup*
Tissue Donors
Vaccines, Conjugate
Antibodies
Complement System Proteins
Immune Sera
Opsonin Proteins
Pneumococcal Vaccines
Vaccines, Conjugate