Highlights • Shigella sonnei is an emergent and highly drug resistant diarrheal pathogen. • The half-life of maternal S. sonnei IgG in infants is 43 days. • Maternal titer, antibody transfer ratio and gestational age influence birth titer. • Incidence of seroconversion in infants in southern Vietnam is 4/100 infant years. • Children should be vaccinated after 5 months of age if a candidate is licensed. Background Shigella 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 results Over 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. Conclusions Maternal 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.
【저자키워드】 Seroconversion, placental transfer, maternal antibody, Shigella,