Fused Mycobacterium tuberculosis multi-stage immunogens with an Fc-delivery system as a promising approach for the development of a tuberculosis vaccine

Infect Genet Evol. 2016 Apr:39:163-172. doi: 10.1016/j.meegid.2016.01.027. Epub 2016 Feb 4.

Abstract

Tuberculosis (TB) remains a major health problem worldwide. Currently, the Bacilli Calmette-Guérin (BCG) is the only available licensed TB vaccine, which has low efficacy in protection against adult pulmonary TB. Therefore, the development of a safe and effective vaccine against TB needs global attention. In the present study, a novel multi-stage subunit vaccine candidate from culture filtrate protein-10 (CFP-10) and heat shock protein X (HspX) of Mycobacterium tuberculosis fused to the Fc domain of mouse IgG2a as a selective delivery system for antigen-presenting cells (APCs) was produced and its immunogenicity assessed. The optimized gene constructs were introduced into pPICZαA expression vectors, and the resultant plasmids (pPICZαA-CFP-10:Hspx:Fcγ2a and pPICZαA-CFP-10:Hspx:His) were transferred into Pichia pastoris by electroporation. The identification of both purified recombinant fusion proteins was evaluated by SDS-PAGE and immunoblotting. Then the immunogenicity of the recombinant proteins with and without BCG was evaluated in BALB/c mice by assessing the level of IFN-γ, IL-12, IL-4, IL-17 and TGF-β cytokines. Both multi-stage vaccines (CFP-10:HspX:Fcγ2a and CFP-10:HspX:His) induced Th1-type cellular responses by producing high level of IFN-γ (272 pg/mL, p<0.001) and IL-12 (191 pg/mL, p<0.001). However, the Fc-tagged recombinant protein induced more effective Th1-type cellular responses with a low level of IL-4 (10 pg/mL) compared to the CFP-10:HspX:His group. The production of IFN-γ to CFP-10:HspX:Fcγ2a was markedly consistent and showed an increasing trend for IL-12 compared with the BCG or CFP-10:HspX:His primed and boosted groups. Findings revealed that CFP-10:Hspx:Fcγ2a fusion protein can elicit strong Th1 antigen-specific immune responses in favor of protective immunity in mice and could provide new insight for introducing an effective multi-stage subunit vaccine against TB.

Keywords: CFP-10; Fc-delivery system; HspX; Multi-stage immunogens; Mycobacterium tuberculosis; Subunit vaccine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigen-Presenting Cells / immunology
  • Antigen-Presenting Cells / metabolism
  • Antigens, Bacterial / chemistry
  • Antigens, Bacterial / genetics
  • Antigens, Bacterial / immunology*
  • Cytokines / immunology
  • Disease Models, Animal
  • Female
  • Gene Expression
  • Immunization
  • Immunoglobulin Fc Fragments / chemistry
  • Immunoglobulin Fc Fragments / genetics
  • Immunoglobulin Fc Fragments / immunology*
  • Mice
  • Models, Molecular
  • Mycobacterium bovis / immunology
  • Mycobacterium tuberculosis / genetics
  • Mycobacterium tuberculosis / immunology*
  • Protein Conformation
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / immunology*
  • Recombinant Fusion Proteins / isolation & purification
  • Th1 Cells / immunology
  • Th1 Cells / metabolism
  • Th2 Cells / immunology
  • Th2 Cells / metabolism
  • Tuberculosis / prevention & control*
  • Tuberculosis Vaccines / genetics
  • Tuberculosis Vaccines / immunology*
  • Vaccines, Subunit / genetics
  • Vaccines, Subunit / immunology

Substances

  • Antigens, Bacterial
  • Cytokines
  • Immunoglobulin Fc Fragments
  • Recombinant Fusion Proteins
  • Tuberculosis Vaccines
  • Vaccines, Subunit
  • Mycobacterium tuberculosis antigens