Protection of mice against fatal pneumococcal challenge by immunization with pneumococcal surface adhesin A (PsaA).

Pneumococcal surface adhesin A (PsaA) is a 37-kDa surface protein present on Streptococcus pneumoniae having significant homology with fimbrial adhesion proteins. Immunization of CBA/CaHNJ Xid mice with PsaA using either complete Freund's or TiterMax adjuvants significantly protected mice against heterologous intravenous challenge with type 3 pneumococcal strain WU2 at doses up to 45 times the LD50. The results indicate that PsaA warrants further evaluation as a vaccine candidate for human pneumococcal disease.