In vivo and in vitro immunogenicity of novel MHC class I presented epitopes to confer protective immunity against chronic HTLV-1 infection

Abstract

Human T-cell leukemia virus type 1 (HTLV-1) has infected approximately 20 million people worldwide. While 90% are asymptomatic, 5% develop severe diseases including adult T-cell leukemia/lymphoka (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). No vaccine against HTLV-1 exists, and screening programs are not universal. However, patients with chronic HTLV-1 infection have high frequencies of HTLV-1-activated CD8+ T cells, and the two main HLA alleles (A2, A24) are present in 88% of infected individuals. We thus utilized an immunoproteomics approach to characterize MHC-I restricted epitopes presented by HLA-A2+, A24+ MT-2 and SLB-1 cell lines. Unlike traditional motif prediction algorithms, this approach identifies epitopes associated with cytotoxic T-cell responses in their naturally processed forms, minimizing differences in antigen processing and protein expression levels. Out of nine identified peptides, we confirmed six novel MHC-I restricted epitopes that were capable of binding HLA-A2 and HLA-A24 alleles and used in vitro and in vivo methods to generate CD8+ T cells specific for each of these peptides. MagPix MILLIPLEX data showed that in vitro generated epitope-specific CD8+ T cells secreted IFN-γ, granzyme B, MIP-1α, TNF-α, perforin and IL-10 when cultured in the presence of MT-2 cell line. Degranulation assay confirmed cytotoxic response through surface expression of CD107 on CD8+ T cells when cultured with MT-2 cells. A CD8+ T-cell killing assay indicated significant antiviral activity of CD8+ T cells specific against all identified peptides. In vivo generated CD8+ T cells similarly demonstrated immunogenicity on ELISpot, CD107 degranulation assay, and MagPix MILLIPLEX analysis. These epitopes are thus candidates for a therapeutic peptide-based vaccine against HTLV-1, and our results provide preclinical data for the advancement of such a vaccine.

PDIA6 promotes pancreatic cancer progression and immune escape through CSN5-mediated deubiquitination of β-catenin and PD-L1

“…6 B). Granzyme B, MIP-1α, IFN-γ, and TNF-α are part of the innate immune response and are mainly produced by NK and natural killer T (NKT) cells [ 22, 23 ]. Interestingly, it was shown that PDIA6 knockdown alone had no significant effect on Granzyme B, MIP-1α, IFN-γ, and TNF-α levels in PC cells.…”

Hijacking Host Immunity by the Human T-Cell Leukemia Virus Type-1: Implications for Therapeutic and Preventive Vaccines

“…Although an HTLV-1 preventative vaccine is feasible, no candidate vaccine has ever proceeded to clinical trial. Vaccine development efforts have used recombinant vaccinia virus vectors, protein immunization, DNA vaccine vectors, and peptide vaccines [ 249 , 250 , 251 , 252 , 253 , 254 , 255 , 256 , 257 , 258 , 259 , 260 , 261 ]. Collectively, these data suggest that an immune-based intervention based on vaccination alone is unlikely to be effective in the context of chronic HTLV-1 infection.…”

A role for an HTLV-1 vaccine?

“…MHC-I-bound HTLV-1 peptides have been identified which give rise to HTLV-1-specific CTLs in vivo ( 79 ). A therapeutic vaccine to activate TAX-specific CTLs was developed using TAX peptide-pulsed dendritic cells, resulting in favorable clinical outcomes in three ATLL patients ( 80 , 81 ).…”