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

Abstract

Pneumococcal surface protein A (PspA) is an important virulence factor of Streptococcus pneumoniae and a candidate for inclusion in future protein-based vaccines. The surface-exposed α-helical region of PspA is immunogenic and frequently cross-reactive, but also variable in structure. Sequence and serological differences in this region divide PspAs into two major families. We showed previously that children preferentially develop antibodies limited to the PspA family of the colonizing strain. In this study, sera of children with history of pneumococcal colonization were analyzed for presence of IgG antibodies to the conserved proline-rich region (PRR) of PspA. The results indicate that children produce antibodies to the PRR upon exposure to pneumococci. The PRR-specific antibodies were elicited regardless of the PspA family of the infecting strain. The results indicate that the PRR antigen elicits broadly cross-reactive antibodies that may have the potential to provide cross-protection against a broad spectrum of pneumococcal strains.