Abstract Background Sapovirus is an important cause of acute gastroenteritis in childhood. While vaccines against sapovirus may reduce gastroenteritis burden, a major challenge to their development is a lack of information about natural immunity. Methods We measured sapovirus-specific IgG in serum collected between 2017 and 2020 of mothers soon after delivery and at 6 time points in Nicaraguan children until 3 years of age (n = 112 dyads), using virus-like particles representing 3 sapovirus genotypes (GI.1, GI.2, GV.1). Results Of the 112 children, 16 (14.3%) experienced at least 1 sapovirus gastroenteritis episode, of which GI.1 was the most common genotype. Seroconversion to GI.1 and GI.2 was most common between 5 and 12 months of age, while seroconversion to GV.1 peaked at 18 to 24 months of age. All children who experienced sapovirus GI.1 gastroenteritis seroconverted and developed genotype-specific IgG. The impact of sapovirus exposure on population immunity was determined by antigenic cartography: newborns share their mothers’ broadly binding IgG responses, which declined at 5 months of age and then increased as infants experienced natural sapovirus infections. Conclusions By tracking humoral immunity to sapovirus over the first 3 years of life, this study provides important insights for the design and timing of future pediatric sapovirus vaccines.

Charting the impact of maternal antibodies and repeat exposures on sapovirus immunity in early childhood from a Nicaraguan birth cohort