Maternal PspA antibodies protect neonates and enable serotype-specific immunity

Maternal antibodies are essential for protecting fetuses and infants with immature immune systems, and maternal vaccination is a promising strategy to prevent neonatal infections. We previously reported the vaccine efficacy of RBD–PspA, a fusion protein combining the receptor-binding domain of parvovirus B19 (B19V) and pneumococcal surface protein A (PspA). Here, we evaluated the protective efficacy of RBD–PspA-induced maternal immunity and its impact on offspring adaptive immunity development. Offspring of vaccinated mothers exhibited anti-RBD and anti-PspA IgG levels comparable to those of their mothers, with neutralizing activity against B19V. These offspring exhibited significantly improved survival following primary challenge with a pneumococcal strain harboring the same PspA family protein. Surviving offspring demonstrated enhanced survival upon re-challenge with a strain of the same capsule-defined serotype but expressing a different PspA family protein. These findings suggest that maternal pneumococcal vaccination protects offspring and permits the development of protective immunity in pups.