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Updated: Mar 3, 2026
A Murine Model of Group B Streptococcus Vaginal Colonization
Published on: November 16, 2016
Association between functional antibody against Group B Streptococcus and maternal and infant colonization in a
Kirsty Le Doare1, Amadou Faal2, Mustapha Jaiteh2
1Centre for International Child Health, Imperial College London, Norfolk Place, London W2 1PG, UK,; Paediatric Infectious Diseases Research Group, St. George's University of London, Cranmer Terrace, London SW17 0TE, UK; Vaccines & Immunity Theme, MRC Unit The Gambia, Atlantic Road, Fajara, Gambia.
Background:
Vertical transmission of Group B Streptococcus (GBS) is a prerequisite for early-onset disease and a consequence of maternal GBS colonization. Disease protection is associated with maternally-derived anti-GBS antibody. Using a novel antibody-mediated C3b/iC3b deposition flow cytometry assay which correlates with opsonic killing we developed a model to assess the impact of maternally-derived functional anti-GBS antibody on infant GBS colonization from birth to day 60-89 of life.
Methods:
Rectovaginal swabs and cord blood (birth) and infant nasopharyngeal/rectal swabs (birth, day 6 and day 60-89) were obtained from 750 mother/infant pairs. Antibody-mediated C3b/iC3b deposition with cord and infant sera was measured by flow cytometry.
Results:
We established that as maternally-derived anti-GBS functional antibody increases, infant colonization decreases at birth and up to three months of life, the critical time window for the development of GBS disease. Further, we observed a serotype (ST)-dependent threshold above which no infant was colonized at birth. Functional antibody above the upper 95th confidence interval for the geometric mean concentration was associated with absence of infant GBS colonization at birth for STII (p<0.001), STIII (p=0.01) and STV (p<0.001). Increased functional antibody was also associated with clearance of GBS between birth and day 60-89.
Conclusions:
Higher concentrations of maternally-derived antibody-mediated complement deposition are associated with a decreased risk of GBS colonization in infants up to day 60-89 of life. Our findings are of relevance to establish thresholds for protection following vaccination of pregnant women with future GBS vaccines.
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