Development of cross-reactive antibodies to the proline-rich region of pneumococcal surface protein A in children

► We measured antibodies to pneumococcal surface protein A (PspA) in children's sera. ► The proline-rich (PR) region of PspA contains conserved epitopes. ► Pneumococcal infection elicits highly cross-reactive antibodies to the PR region. ► The PR region is an attractive candidate for inclusion in a protein-based vaccine.