Nanoscale Peptide Self-assemblies Boost BCG-primed Cellular Immunity Against Mycobacterium tuberculosis

Sci Rep. 2018 Aug 21;8(1):12519. doi: 10.1038/s41598-018-31089-y.

Abstract

Bacillus Calmette-Guerin (BCG) is the only vaccine against TB and has limited protection efficacy, which wanes past adolescence. Multifunctional CD8+ T cells (IFN-γ+/TNF-α+/IL-2+) are associated with lower reactivation risk and enhanced control of active Mtb infection. Since boosting with BCG is contraindicated, booster vaccines that augment T cell immunity in the lungs of BCG-vaccinated individuals are urgently needed. We developed a vaccination strategy based on self-assembling peptide nanofibers presenting Mtb-specific CD8+ or CD4+ T cell epitopes that induce high frequency and antigen-specific effector memory T cells producing IFN-γ and IL-2. Intranasal immunization with peptide nanofibers was well tolerated in mice leading to increased antigen-specific CD8+ T cell population in the lungs. Co-assembled nanofibers of CD8+ T cell epitopes and toll-like receptor 2 (TLR2) agonists induced a 8-fold expansion in multifunctional CD8+ T cell populations in the lungs of vaccinated mice. Aerosol challenge with Mtb in BCG-primed and nanofiber-boosted mice provided an additional 0.5-log CFU reduction in lung bacterial load and indicating enhanced protection compared to BCG alone. Together, these data suggest that heterologous prime-boost with BCG and peptide nanofiber vaccines induces cell mediated immunity in the lung, reduces bacterial burden, and is a potentially safer alternative for boosting BCG-primed immunity.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Administration, Intranasal
  • Animals
  • Antigens, Bacterial / chemistry*
  • BCG Vaccine / administration & dosage
  • BCG Vaccine / immunology
  • CD4-Positive T-Lymphocytes / metabolism
  • CD8-Positive T-Lymphocytes / metabolism
  • Epitopes, B-Lymphocyte / administration & dosage*
  • Epitopes, B-Lymphocyte / immunology
  • Epitopes, T-Lymphocyte / administration & dosage*
  • Epitopes, T-Lymphocyte / immunology
  • Immunization, Secondary
  • Infusions, Parenteral
  • Interferon-gamma / metabolism
  • Interleukin-2 / metabolism
  • Mice
  • Mycobacterium tuberculosis / immunology*
  • Nanofibers
  • Peptides / administration & dosage*
  • Peptides / chemical synthesis
  • Peptides / immunology
  • T-Lymphocytes / immunology*

Substances

  • Antigens, Bacterial
  • BCG Vaccine
  • Epitopes, B-Lymphocyte
  • Epitopes, T-Lymphocyte
  • IFNG protein, mouse
  • Interleukin-2
  • Peptides
  • Interferon-gamma