Multi-level Strategy for Identifying Proteasome-Catalyzed Spliced Epitopes Targeted by CD8 + T Cells during Bacterial Infection

Cell Rep. 2017 Aug 1;20(5):1242-1253. doi: 10.1016/j.celrep.2017.07.026.

Abstract

Proteasome-catalyzed peptide splicing (PCPS) generates peptides that are presented by MHC class I molecules, but because their identification is challenging, the immunological relevance of spliced peptides remains unclear. Here, we developed a reverse immunology-based multi-level approach to identify proteasome-generated spliced epitopes. Applying this strategy to a murine Listeria monocytogenes infection model, we identified two spliced epitopes within the secreted bacterial phospholipase PlcB that primed antigen-specific CD8+ T cells in L. monocytogenes-infected mice. While reacting to the spliced epitopes, these CD8+ T cells failed to recognize the non-spliced peptide parts in the context of their natural flanking sequences. Thus, we here show that PCPS expands the CD8+ T cell response against L. monocytogenes by exposing spliced epitopes on the cell surface. Moreover, our multi-level strategy opens up opportunities to systematically investigate proteins for spliced epitope candidates and thus strategies for immunotherapies or vaccine design.

Keywords: Listeria monocytogenes; antigen presentation; in silico analysis; intracelllular bacteria; peptide splicing; proteasome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CD8-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / pathology
  • Epitopes, T-Lymphocyte / genetics
  • Epitopes, T-Lymphocyte / immunology*
  • Listeria monocytogenes / immunology*
  • Listeriosis / genetics
  • Listeriosis / immunology*
  • Listeriosis / pathology
  • Mice
  • Proteasome Endopeptidase Complex / genetics
  • Proteasome Endopeptidase Complex / immunology*

Substances

  • Epitopes, T-Lymphocyte
  • Proteasome Endopeptidase Complex