Novel Multiplex Immunoassays for Quantification of IgG against Group B <italic toggle="yes">Streptococcus</italic> Capsular Polysaccharides in Human Sera

ABSTRACT Group B Streptococcus (GBS) infections constitute a major cause of invasive disease during the first three months of life and an unmet medical need that could be addressed by maternal vaccination. The GBS capsular polysaccharides (CPSs) have shown promise as vaccine targets in clinical stud...

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Autores principales:	Giada Buffi, Bruno Galletti, Maria Stella, Daniela Proietti, Evita Balducci, Maria Rosaria Romano, Elena Mori, Monica Fabbrini, Marzia Monica Giuliani, Francesco Berti, Immaculada Margarit
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2019
Materias:	GBS capsular polysaccharides immunoassay multiplex neonatal infection Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/cc73657a23bd4115914741b7c472452e
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spelling	oai:doaj.org-article:cc73657a23bd4115914741b7c472452e2021-11-15T15:22:26ZNovel Multiplex Immunoassays for Quantification of IgG against Group B <italic toggle="yes">Streptococcus</italic> Capsular Polysaccharides in Human Sera10.1128/mSphere.00273-192379-5042https://doaj.org/article/cc73657a23bd4115914741b7c472452e2019-08-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mSphere.00273-19https://doaj.org/toc/2379-5042ABSTRACT Group B Streptococcus (GBS) infections constitute a major cause of invasive disease during the first three months of life and an unmet medical need that could be addressed by maternal vaccination. The GBS capsular polysaccharides (CPSs) have shown promise as vaccine targets in clinical studies. A highly specific serological assay to quantify maternal and neonatal anti-CPS antibody levels will be instrumental for GBS vaccine licensure. Here, we describe the development and comparison of two novel multiplex immunoassays (MIAs) based on the Luminex technology for the quantification of IgG antibodies recognizing the five most frequent GBS capsular variants (Ia, Ib, II, III, and V) out of the ten types identified. The first assay is based on the use of biotinylated CPSs coupled to streptavidin-derivatized magnetic microspheres (Biotin-CPS MIA), while the second is a sandwich assay with plain CPSs coupled to magnetic microspheres coated with polysaccharide-specific mouse monoclonal antibodies (Sandwich MIA). Both assays showed good specificity, linearity, and precision, although the Biotin-CPS MIA presented higher sensitivity and lower complexity than the Sandwich MIA. A panel of human sera representing a wide range of anti-CPS IgG concentrations was tested in parallel by the two assays, which resulted in comparable titers. Our data support the preservation of antigenic epitopes in the biotinylated polysaccharides and the suitability of the Biotin-CPS MIA for the precise determination of GBS anti-CPS IgG concentrations in human sera. IMPORTANCE Group B streptococcal infections can cause death in neonates up to 3 months of age. Intrapartum antibiotic prophylaxis in GBS-colonized mothers has limited early infections but has no impact after the first week of life. The development of a maternal vaccine to address this unmet medical need has been identified as a priority by the World Health Organization, and the GBS CPSs are considered the best antigen targets. However, to date there are no accepted standardized assays to measure immune responses to the investigational vaccines and for establishment of serocorrelates of protection. Here, we describe the performance of two microsphere-based pentaplex immunoassays for the determination of antibodies recognizing the five most frequent GBS serotypes. Our data confirm that an assay based on biotinylated polysaccharides coupled to streptavidin microspheres would be suitable for the intended purpose.Giada BuffiBruno GallettiMaria StellaDaniela ProiettiEvita BalducciMaria Rosaria RomanoElena MoriMonica FabbriniMarzia Monica GiulianiFrancesco BertiImmaculada MargaritAmerican Society for MicrobiologyarticleGBScapsular polysaccharidesimmunoassaymultiplexneonatal infectionMicrobiologyQR1-502ENmSphere, Vol 4, Iss 4 (2019)
institution	DOAJ
collection	DOAJ
language	EN
topic	GBS capsular polysaccharides immunoassay multiplex neonatal infection Microbiology QR1-502
spellingShingle	GBS capsular polysaccharides immunoassay multiplex neonatal infection Microbiology QR1-502 Giada Buffi Bruno Galletti Maria Stella Daniela Proietti Evita Balducci Maria Rosaria Romano Elena Mori Monica Fabbrini Marzia Monica Giuliani Francesco Berti Immaculada Margarit Novel Multiplex Immunoassays for Quantification of IgG against Group B <italic toggle="yes">Streptococcus</italic> Capsular Polysaccharides in Human Sera
description	ABSTRACT Group B Streptococcus (GBS) infections constitute a major cause of invasive disease during the first three months of life and an unmet medical need that could be addressed by maternal vaccination. The GBS capsular polysaccharides (CPSs) have shown promise as vaccine targets in clinical studies. A highly specific serological assay to quantify maternal and neonatal anti-CPS antibody levels will be instrumental for GBS vaccine licensure. Here, we describe the development and comparison of two novel multiplex immunoassays (MIAs) based on the Luminex technology for the quantification of IgG antibodies recognizing the five most frequent GBS capsular variants (Ia, Ib, II, III, and V) out of the ten types identified. The first assay is based on the use of biotinylated CPSs coupled to streptavidin-derivatized magnetic microspheres (Biotin-CPS MIA), while the second is a sandwich assay with plain CPSs coupled to magnetic microspheres coated with polysaccharide-specific mouse monoclonal antibodies (Sandwich MIA). Both assays showed good specificity, linearity, and precision, although the Biotin-CPS MIA presented higher sensitivity and lower complexity than the Sandwich MIA. A panel of human sera representing a wide range of anti-CPS IgG concentrations was tested in parallel by the two assays, which resulted in comparable titers. Our data support the preservation of antigenic epitopes in the biotinylated polysaccharides and the suitability of the Biotin-CPS MIA for the precise determination of GBS anti-CPS IgG concentrations in human sera. IMPORTANCE Group B streptococcal infections can cause death in neonates up to 3 months of age. Intrapartum antibiotic prophylaxis in GBS-colonized mothers has limited early infections but has no impact after the first week of life. The development of a maternal vaccine to address this unmet medical need has been identified as a priority by the World Health Organization, and the GBS CPSs are considered the best antigen targets. However, to date there are no accepted standardized assays to measure immune responses to the investigational vaccines and for establishment of serocorrelates of protection. Here, we describe the performance of two microsphere-based pentaplex immunoassays for the determination of antibodies recognizing the five most frequent GBS serotypes. Our data confirm that an assay based on biotinylated polysaccharides coupled to streptavidin microspheres would be suitable for the intended purpose.
format	article
author	Giada Buffi Bruno Galletti Maria Stella Daniela Proietti Evita Balducci Maria Rosaria Romano Elena Mori Monica Fabbrini Marzia Monica Giuliani Francesco Berti Immaculada Margarit
author_facet	Giada Buffi Bruno Galletti Maria Stella Daniela Proietti Evita Balducci Maria Rosaria Romano Elena Mori Monica Fabbrini Marzia Monica Giuliani Francesco Berti Immaculada Margarit
author_sort	Giada Buffi
title	Novel Multiplex Immunoassays for Quantification of IgG against Group B <italic toggle="yes">Streptococcus</italic> Capsular Polysaccharides in Human Sera
title_short	Novel Multiplex Immunoassays for Quantification of IgG against Group B <italic toggle="yes">Streptococcus</italic> Capsular Polysaccharides in Human Sera
title_full	Novel Multiplex Immunoassays for Quantification of IgG against Group B <italic toggle="yes">Streptococcus</italic> Capsular Polysaccharides in Human Sera
title_fullStr	Novel Multiplex Immunoassays for Quantification of IgG against Group B <italic toggle="yes">Streptococcus</italic> Capsular Polysaccharides in Human Sera
title_full_unstemmed	Novel Multiplex Immunoassays for Quantification of IgG against Group B <italic toggle="yes">Streptococcus</italic> Capsular Polysaccharides in Human Sera
title_sort	novel multiplex immunoassays for quantification of igg against group b <italic toggle="yes">streptococcus</italic> capsular polysaccharides in human sera
publisher	American Society for Microbiology
publishDate	2019
url	https://doaj.org/article/cc73657a23bd4115914741b7c472452e
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Novel Multiplex Immunoassays for Quantification of IgG against Group B <italic toggle="yes">Streptococcus</italic> Capsular Polysaccharides in Human Sera

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