Streptococcus pneumoniae is a respiratory pathogen causing severe lung infection that may lead to complications such as bacteremia. Current polysaccharide vaccines have limited serotype coverage and therefore cannot provide maximal and long-term protection. Global efforts are being made to develop a conserved protein vaccine candidate. PrtA， a pneumococcal surface protein， was identified by screening a pneumococcal genomic expression library using convalescent patient serum. The prtA gene is prevalent and conserved among S. pneumoniae strains. Its protective efficacy， however， has not been described. Mucosal immunization could sensitize both local and systemic immunity， which would be an ideal scenari... More