Protection induced by pneumococcal surface protein A (PspA) is enhanced by conjugation to a Streptococcus pneumoniae capsular polysaccharide.
The currently available anti-pneumococcal vaccines are based on capsular polysaccharide (PS), plain or conjugated to a carrier protein. Conjugated vaccines are expensive products, especially in the case of pneumococcus, in which reasonable coverage requires from 7 to 13 serotypes. To obtain increased coverage with fewer components, we evaluated the immunogenicity of the pneumococcal surface protein A (PspA), conjugated to capsular polysaccharide serotype 23F, aiming at induction of an immune response against both components. Mice immunized with PS23F-rPspA1 conjugate produced antibodies against both PS and rPspA1, comparable or slightly higher than that obtained by free PS. The immunized animals challenged with a lethal dose of a virulent strain bearing a homologous PspA, showed that the PS23F-rPspA1 conjugate induced higher survival than rPspA1 alone or in combination with PS. This increased protection was shown to correlate with the enhanced capacity of the antibodies to bind to the pneumococcal surface and to induce complement deposition. Our results indicate that the use of PS-PspA conjugates may be a way to increase coverage against pneumococci with fewer components.
Csordas
Fátima C L
FC
Centro de Biotecnologia, Instituto Butantan, Avenida Vital Brasil 1500, CEP 05503, São Paulo, Brazil.
Perciani
Cátia T
CT
Darrieux
Michelle
M
Gonçalves
Viviane M
VM
Cabrera-Crespo
Joaquim
J
Takagi
Mickie
M
Sbrogio-Almeida
Maria E
ME
Leite
Luciana C C
LC
Tanizaki
Martha M
MM
D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis / Q000096:biosynthesis; D001426:Bacterial Proteins / Q000276:immunology*; D003165:Complement System Proteins / Q000096:biosynthesis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D022242:Pneumococcal Vaccines / Q000276:immunology* / Q000627:therapeutic use*; D011134:Polysaccharides / Q000276:immunology* / Q000627:therapeutic use*; D018074:Vaccines, Conjugate / Q000276:immunology / Q000627:therapeutic use; D014614:Vaccines, Synthetic / Q000276:immunology / Q000627:therapeutic use
D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D022242:Pneumococcal Vaccines; D011134:Polysaccharides; D018074:Vaccines, Conjugate; D014614:Vaccines, Synthetic; C051592:pneumococcal surface protein A; D003165:Complement System Proteins