title: Recombinant BCG expressing a PspA-PdT fusion protein protects mice against pneumococcal lethal challenge in a prime-boost strategy.
abstract: Pneumococcal proteins have been evaluated as genetically-conserved potential vaccine candidates. We have previously demonstrated that a fragment of PspA in fusion with PdT (rPspA-PdT) induced protective immune responses in mice. However, purified proteins have shown poor immunogenicity and often require the combination with strong adjuvants and booster doses. Here, we investigated the use of a Bacillus Calmette-Guérin (BCG) strain, a well-established prophylactic vaccine for tuberculosis with known adjuvant properties, for delivery of the PspA-PdT fusion protein. Immunization of mice in a prime-boost strategy, using rPspA-PdT as a boost, demonstrated that rBCG PspA-PdT/rPspA-PdT was able to induce an antibody response against both proteins, promoting an IgG1 to IgG2 antibody isotype shift. Sera from rBCG PspA-PdT/rPspA-PdT immunized mice showed antibodies able to bind to the pneumococcal surface and promoted higher complement deposition when compared with WT-BCG/rPspA-PdT or a single dose of rPspA-PdT. In addition, these antisera inhibited the cytolytic activity of Ply. Production of interleukin-6 (IL-6), gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α) was increased in splenocytes culture. Furthermore, a higher expression of CD69 early activation molecule was observed on splenic CD4+T cells from mice immunized with rBCG PspA-PdT before and after the protein booster dose. Finally, immunization with rBCG PspA-PdT/rPspA-PdT protected mice against pneumococcal lethal challenge. These results support the further investigation of recombinant BCG strains to express pneumococcal proteins, which could be administered in early stages of life and lead to protective pneumococcal immunity in infants and children.
authors.affiliation: Centro de Biotecnologia, Instituto Butantan, Brazil; Programa De Pós-Graduação Interunidades em Biotecnologia USP-I.Butantan-IPT, Brazil.
authors.forename: Cibelly
authors.initials: C
authors.lastname: Goulart
authors.affiliation: Centro de Biotecnologia, Instituto Butantan, Brazil.
authors.forename: Dunia
authors.initials: D
authors.lastname: Rodriguez
authors.affiliation: Centro de Biotecnologia, Instituto Butantan, Brazil.
authors.forename: Alex I
authors.initials: AI
authors.lastname: Kanno
authors.affiliation: Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, USA.
authors.forename: Ying-Jie
authors.initials: YJ
authors.lastname: Lu
authors.affiliation: Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Malley
authors.affiliation: Centro de Biotecnologia, Instituto Butantan, Brazil. Electronic address: luciana.leite@butantan.gov.br.
authors.forename: Luciana C C
authors.initials: LC
authors.lastname: Leite
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D015703:Antigens, CD / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry / Q000276:immunology; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D004337:Drug Carriers; D005260:Female; D007115:Immunization Schedule; D007074:Immunoglobulin G / Q000097:blood; D037181:Lectins, C-Type / Q000032:analysis; D008810:Mice, Inbred C57BL; D009163:Mycobacterium bovis / Q000235:genetics*; D011008:Pneumococcal Infections / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology*; D016019:Survival Analysis; D016896:Treatment Outcome; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D000099192:CD69 Antigens
chemical_list: D000907:Antibodies, Bacterial; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D001426:Bacterial Proteins; D016207:Cytokines; D004337:Drug Carriers; D007074:Immunoglobulin G; D037181:Lectins, C-Type; D022242:Pneumococcal Vaccines; D011993:Recombinant Fusion Proteins; D014614:Vaccines, Synthetic; D000099192:CD69 Antigens; C518593:pertussis toxin-diphtheria toxin-tetanus toxin fusion protein; C051592:pneumococcal surface protein A
keywords: PdT; PspA; Recombinant BCG; Streptococcus pneumoniae