RESUMEN
Objective To compare the immunogenicity of pneumococcal surface adhesion A (PsaA) and pneumococcal surface protein A (PspA). Methods The variability of the genes and the expressed pneumococcal proteins PsaA and PspA was investigated by electrophoresis. Cross-reactivity of proteins with the antibodies induced by the corresponding proteins of Streptococcus pneumoniae serotype 5, 6B,1, 19F and 23F was researched by Western blot. The enzyme-linked immunosorbent assay (ELISA) was adopted to detect the antibody subclasses and the accessibility of antibodies induced by PsaA and PspA to the surface of the above intact strains. Cross-protection against challenging with Streptococcus pneumoniae strains was indagated in mice. Results Both proteins showed to induce the similar level of antibody subclasses.This study demonstrated that cross-reactivity of pneumococcal PspA was restricted in the same clade, which showed less extensive than pneumococcal protein PsaA. But antibody induced by pneumococcal protein PspA could be bound to the surface of the intact strains, which conduced the stronger cross-protection against inva sive strains. Conclusion The mice immunized with PspA protein cross-protected well against the invasive strains in which PspA belonged to the same clade 1 of family 1. It showed that pneumococcal protein PspA was more effective than PsaA in protection as composition of vaccine.