The identification of a common pathogen-specific HLA class I A*0201-restricted cytotoxic T cell epitope encoded within the heat shock protein 65

Abstract

Bacterial antigens recognized by CD8+ T cells in the context of MHC class I are thought to play a crucial role in protection against pathogenic intracellular bacteria. Here, we demonstrate the induction of HLA‐A*0201‐restricted CD8+ T cell responses against six new high‐affinity HLA‐A*0201‐binding CTL epitopes, encoded within an immunodominant and highly conserved antigen of Mycobacteria, the heat shock protein 65 (hsp65). One of these epitopes, Mhsp65(9369), is identical in a large number of pathogenic bacteria, and is recognized in a CD8‐independent fashion. Mhsp65(9369) could be presented by either mycobacterial hsp65‐pulsed target cells or BCG‐infected macrophages. Interestingly, T cells specific for this epitope did not recognize the corresponding human hsp65 homologue, probably due to structural differences as revealed by modeling studies. Furthermore, in vitro proteasome digestion analyses show that, whereas the mycobacterial hsp65 epitope is efficiently generated, the human hsp65 homologue is not, thus avoiding the induction of autoreactivity. Collectively, these findings describe high‐affinity HLA class I‐binding epitopes that are naturally processed and are recognized efficiently by MHC class I‐restricted CD8+ T cells, providing a rational basis for the development of subunit vaccine strategies against tuberculosis and other intracellular infectious diseases.

Protective Efficacy of a DNA Influenza Virus Vaccine Is Markedly Increased by the Coadministration of a Schiff Base-Forming Drug

“…This shows that tucaresol enhances the CTL activity of P-NP immunization and results in an almost 10-fold increase in the cytotoxic activity. These data are similar to those obtained in previous studies with tucaresol (4,6). In line with our present results, we did not detect cytolytic response using splenocytes from mice immunized only with a plasmid coding for a mycobacterial heat shock protein (Mhsp65) while we were able to detect a strong cytolytic response using splenocytes from the Mhsp65-immunized mice that have also received tucaresol (4-6).…”

Identification by Mass Spectrometry of CD8+-T-CellMycobacterium tuberculosisEpitopes within the Rv0341 Gene Product

“…The first was derived from M. tuberculosis heat shock protein hsp65, a protein previously identified as a target for CD4 ϩ T cells (38) and found to induce protection in murine models when administered as a DNA vaccine (9). Recently, this peptide and others derived from hsp65 have been shown to associate with the HLA-A0201 molecule and induce CTL responses in HLA-A0201/K b transgenic mice (12). The second peptide was derived from galactofuranosyl transferase (33), an M. tuberculosis protein not previously shown to be recognized by the immune system.…”

Marked Enhancement of the Antigen-Specific Immune Response by Combining Plasmid DNA-Based Immunization with a Schiff Base-Forming Drug

“…HLA-A‫/1020ء‬K b transgenic mice (kindly provided by L. Sherman, Scripps Laboratories, San Diego, Calif.) used in this study have been described previously (40). This strain was used to enable the measurement of the cytotoxic T-cell response to a defined T-cell epitope restricted by HLA-A2 (4,5). The surface expression of HLA-A‫/1020ء‬K b was confirmed by using an HLA-A‫-1020ء‬ specific fluorescein isothiocyanate-conjugated monoclonal antibody (One Lambda, Canoga Park, Calif.) and assessed by flow cytometry using FACScan (Becton Dickinson & Co., Mountain View, Calif.).…”

“…This has been demonstrated in two models for DNA vaccination previously established for induction of specific immune responses against viral (3) and mycobacterial (4,5) antigens. The immunopotentiating effect of tucaresol has been reported to be mediated by delivery of costimulatory signals involved in the priming of T-cell responses through the substitution of carbonyl groups naturally provided by antigen-presenting cells.…”