Design and Characterization of a Multistage Peptide-Based Vaccine Platform to Target Mycobacterium tuberculosis Infection

Bioconjug Chem. 2023 Oct 18;34(10):1738-1753. doi: 10.1021/acs.bioconjchem.3c00273. Epub 2023 Aug 22.

Abstract

The complex immunopathology ofMycobacterium tuberculosis(Mtb) is one of the main challenges in developing a novel vaccine against this pathogen, particularly regarding eliciting protection against both active and latent stages. Multistage vaccines, which contain antigens expressed in both phases, represent a promising strategy for addressing this issue, as testified by the tuberculosis vaccine clinical pipeline. Given this approach, we designed and characterized a multistage peptide-based vaccine platform containing CD4+ and CD8+ T cell epitopes previously validated for inducing a relevant T cell response against Mtb. After preliminary screening, CFP10 (32-39), GlfT2 (4-12), HBHA (185-194), and PPE15 (1-15) were selected as promising candidates, and we proved that the PM1 pool of these peptides triggered a T cell response in Mtb-sensitized human peripheral blood mononuclear cells (PBMCs). Taking advantage of the use of thiol-maleimide chemoselective ligation, we synthesized a multiepitope conjugate (Ac-CGHP). Our results showed a structure-activity relationship between the conjugation and a higher tendency to fold and assume an ordered secondary structure. Moreover, the palmitoylated conjugate (Pal-CGHP) comprising the same peptide antigens was associated with an enhanced cellular uptake in human and murine antigen-presenting cells and a better immunogenicity profile. Immunization study, conducted in BALB/c mice, showed that Pal-CGHP induced a significantly higher T cell proliferation and production of IFNγ and TNFα over PM1 formulated in the Sigma Adjuvant System.

MeSH terms

  • Animals
  • Antigens, Bacterial
  • CD4-Positive T-Lymphocytes
  • CD8-Positive T-Lymphocytes
  • Epitopes, T-Lymphocyte
  • Humans
  • Leukocytes, Mononuclear
  • Mice
  • Mycobacterium tuberculosis*
  • Peptides
  • Tuberculosis Vaccines*
  • Tuberculosis* / prevention & control

Substances

  • Antigens, Bacterial
  • Tuberculosis Vaccines
  • Epitopes, T-Lymphocyte
  • Peptides