E.W. "Al" Thrasher
Status: Funded - Open
Group-B streptococci: developing a correlate of protection for future vaccine trials in Gambian women and infants
Beate Kampmann, M.D., FRCPCH, DTM&H, Ph.D.
BACKGROUND: Group-B Streptococcal (GBS) disease is a major cause of infant mortality and morbidity globally. Phase III trials of maternal GBS vaccines are hampered by large sample numbers required to prove efficacy. If laboratory markers predicting vaccine efficacy could be identified, this would be a major step forward for the field.
GAP: The effect of maternal GBS carriage on serotype-specific antibody transfer to her infant and subsequent antibody function has not been evaluated. We also do not know the natural history of decline in antibody in infant blood and if/how it might protect from GBS carriage and what role breast milk can play.
HYPOTHESIS: 1. What is the correlation between maternal and infant anti-GBS antibody levels and infant colonization. 2. Can maternal antibody concentration be used as a surrogate marker of protection from carriage and thus possibly disease in Gambian infants.
METHODS: We will examine the link between maternal carriage, infant colonization and antibody-responses by studying both trans-placental antibody and antibody contained in breast milk.
Study Design: A prospective cohort study of low-risk, third trimester pregnant women attending antenatal clinics in The Gambia and their infants (0-89 days).
Sample Collection: swabs from mother and baby at birth, 6-7 days and 2-3 months; cord blood for maternal antibody; infant blood sample at 2- 3 months for antibody persistence; breast milk at birth, 6-7 days and 2-3 months for antibody persistence.
IMPACT: We wish to examine whether GBS vaccine candidates currently under development would be effective in this region in West Africa. We will investigate serotype-specific antibody transfer and neonatal antibody persistence and in-vitro functionality to gain insight into the potential of such assays to be used as a surrogate marker of protection from disease.
Imperial College London
United Kingdom, The Gambia