Interlaboratory comparison of a multiplex immunoassay that measures human serum IgG antibodies against six-group B streptococcus polysaccharides

ABSTRACT

Measurement of IgG antibodies against group B streptococcus (GBS) capsular polysaccharide (CPS) by use of a standardized and internationally accepted multiplex immunoassay is important for the evaluation of candidate maternal GBS vaccines in order to compare results across studies. A standardized assay is also required if serocorrelates of protection against invasive GBS disease are to be established in infant sera for the six predominant GBS serotypes since it would permit the comparison of results across the six serotypes. We undertook an interlaboratory study across five laboratories that used standardized assay reagents and protocols with a panel of 44 human sera to measure IgG antibodies against GBS CPS serotypes Ia, Ib, II, III, IV, and V. The within-laboratory intermediate precision, which included factors like the lot of coated beads, laboratory analyst, and day, was generally below 20% relative standard deviation (RSD) for all six serotypes, across all five laboratories. The cross-laboratory reproducibility was < 25% RSD for all six serotypes, which demonstrated the consistency of results across the different laboratories. Additionally, anti-CPS IgG concentrations for the 44-member human serum panel were established. The results of this study showed assay robustness and that the resultant anti-CPS IgG concentrations were reproducible across laboratories for the six GBS CPS serotypes when the standardized assay was used.

KEYWORDS:

• Group B streptococcus
• maternal
• neonatal
• correlate of protection
• vaccines

Acknowledgments

The authors would like to thank the advisory group members of the GASTON Consortium: David Goldblatt, Beate Kampmann, Moon Nahm, Paul Heath, Benjamin Wizel, Mark Alderson, and Seannette Williams. The authors acknowledge Christina D’Arco (Pfizer) for editorial support.

Disclosure statement

Authors who are employees of Pfizer may, as a consequence, be shareholders of Pfizer Inc.

Author contributions

Conceptualisation: M.A.G., C.D.G., P.C.G, C.Y.T., A.M., A.G., G.A., and K.L.D.; data curation: N.A., C.Y.T., A.M., M.A.G., C.D.G. and K.L.D.; formal analysis: N.A., C.Y.T., A.M. and K.L.D.; funding acquisition: A.G., K.L.D.; investigation; M.A.G., A.A., N.A., C.B., S.B., A.F., P.C.G., C.D.G., T.H., B.H., A.I., S.M., P.M., M.M., F.M., A.M., J.R., S.S., R.S., C.Y.T., S.T., G.K., A.G., and K.L.D.; methodology: M.A.G., A.A., N.A., C.B., S.B., A.F., P.C.G., C.D.G., T.H., B.H., A.I., S.M., P.M., M.M., F.M., A.M., J.R., S.S., R.S., C.Y.T., S.T., G.K., A.G., and K.L.D.; project administration: M.A.G., A.A., N.A., C.B., S.B., A.F., P.C.G., C.D.G., T.H., B.H., A.I., S.M., P.M., M.M., F.M., A.M., J.R., S.S., R.S., C.Y.T., S.T., G.K., A.G., and K.L.D.; supervision: M.A.G., A.F., P.C.G., C.D.G., B.H., S.M., P.M., M.M., F.M., J.R., R.S., S.T., G.K., A.G., and K.L.D.; visualization: M.A.G. and K.L.D.; writing – original draft: M.A.G., C.D.G., A.M., T.H. and K.L.D.; writing – review and editing: M.A.G., A.A., N.A., C.B., S.B., A.F., P.C.G., C.D.G., T.H., B.H., A.I., S.M., P.M., M.M., F.M., A.M., J.R., S.S., R.S., C.Y.T., S.T., G.K., A.G., and K.L.D. All authors have read and agreed to the published version of the manuscript.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website at https://doi.org/10.1080/21645515.2024.2330138.

Additional information

Funding

This work was funded by the BILL & MELINDA GATES FOUNDATION, Seattle, WA, INV-008343. The funders had no role in the design, analysis, or interpretation of the data in this research study, in the writing of the report, or the decision to publish.