Abstract
BackgroundShigella sonnei is an emergent and major diarrheal pathogen for which there is currently no vaccine. We aimed to quantify duration of maternal antibody against S. sonnei and investigate transplacental IgG transfer in a birth cohort in southern Vietnam. Methods and resultsOver 500-paired maternal/infant plasma samples were evaluated for presence of anti-S. sonnei-O IgG and IgM. Longitudinal plasma samples allowed for the estimation of the median half-life of maternal anti-S. sonnei-O IgG, which was 43 days (95% confidence interval: 41–45 days). Additionally, half of infants lacked a detectable titer by 19 weeks of age. Lower cord titers were associated with greater increases in S. sonnei IgG over the first year of life, and the incidence of S. sonnei seroconversion was estimated to be 4/100 infant years. Maternal IgG titer, the ratio of antibody transfer, the season of birth and gestational age were significantly associated with cord titer. ConclusionsMaternal anti-S. sonnei-O IgG is efficiently transferred across the placenta and anti-S. sonnei-O maternal IgG declines rapidly after birth and is undetectable after 5 months in the majority of children. Preterm neonates and children born to mothers with low IgG titers have lower cord titers and therefore may be at greater risk of seroconversion in infancy.
Highlights
The bacterial genus Shigella is a major contributor to the global burden of diarrheal disease
We firstly validated the anti-S. sonnei-O enzyme-linked immunosorbent assay (ELISA) in a population of Vietnamese children hospitalized with dysentery with acute and convalescent plasma samples
All tested (7/7; 100%) stool culture-positive S. sonnei cases presenting to hospital had >4 fold rise in IgG titer regardless of the number of days between the acute and convalescent samples
Summary
The bacterial genus Shigella is a major contributor to the global burden of diarrheal disease This genus of enteric pathogens is typically associated with disease in children under 5 years of age in industrializing regions [1], and is estimated to be responsible. Lower cord titers were associated with greater increases in S. sonnei IgG over the first year of life, and the incidence of S. sonnei seroconversion was estimated to be 4/100 infant years. Maternal IgG titer, the ratio of antibody transfer, the season of birth and gestational age were significantly associated with cord titer. Preterm neonates and children born to mothers with low IgG titers have lower cord titers and may be at greater risk of seroconversion in infancy
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