| Summary: | Streptococcus pneumoniae is the leading cause of vaccine-preventable bacterial disease worldwide. Pneumococcal protein antigens are currently under study as potential new generation of vaccines which might protect against multiple serotypes. The aim of this study was to evaluate the mechanisms of naturally-acquired human immune responses to pneumococcal protein antigens and investigate the evolution and maturation of these responses in an area with a high burden of carriage and disease. Nasopharyngeal swabs were cultured for pneumococcus to determine carriage rates. Blood mononuclear cells obtained from healthy adults, children and babies were stimulated with culture supenatants derived from a standard strain D39 wild-type and isogenic mutant strains lacking pneumolysin (Ply-) or choline binding protein A (CbpA-), and recombinant pneumolysin (rPly). In vitro immune responses to these antigens were measured by cellular proliferation, ELISPOT for IL-10- and IFN-y-producing cells and bio-plex cytokine assays. The cellular source of the cytokines was assessed by intracellular cytokine staining (ICS).
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