A novel CD4 T-cell epitope described from one of the cervical cancer patients vaccinated with HPV 16 or 18 E7-pulsed dendritic cells

Abstract

Previously, safety and immunogenicity of human papillomavirus type 16 (HPV16) or 18 E7-pulsed dendritic cells (DC) vaccinations were demonstrated in a dose-escalation Phase I clinical trial which enrolled ten patients diagnosed with stage IB or IIA cervical cancer (nine HPV 16-positive, one HPV 18-positive). The goal of the study was to define the T-cell epitopes of HPV 16 or 18 E7 protein in these patients in order to develop new strategies for treating HPV-associated malignancies. This was accomplished through establishing T-cell lines by stimulating peripheral blood mononuclear cells with autologous mature DC pulsed with the HPV 16 or 18 E7 protein, examining the T-cell responses using ELISPOT assays, and isolating E7-specific T-cell clones based on IFN-γ secretion. Then, the epitope was characterized in terms of its core sequence and the restriction element. Twelve T-cell lines from eight subjects (seven HPV 16-positive, one HPV 18-positive) were evaluated. Positive Tcell responses were demonstrated in four subjects (all HPV 16-positive). All four were positive for the HPV 16 E7 46-70 (EPDRAHYNIVTFCCKCDSTLRLCVQ) region. T-cell clones specific for the E7 47-70 region were isolated from one of the subjects. Further analyses revealed a novel, naturally processed, CD4 T-cell epitope, E7 58-68 (CCKCDSTLRLC), restricted by the HLA-DR17 molecule.

Identification of promiscuous HPV16-derived T helper cell epitopes for therapeutic HPV vaccine design

“…However, the development of successful anti‐HPV immunotherapy has proven to be a challenging task. Recently, there has been considerable interest to identify HPV E6‐ and E7‐derived CD4+ T helper cell epitopes using overlapping peptide pools and to include them in peptide‐based therapeutic vaccine design . Our approach in the current study was to use computational HLA class II prediction algorithms to define HPV16‐derived CD4+ T cell epitopes, which bind promiscuously to the binding groove of multiple HLA‐DR molecules.…”

“…Recently, there has been considerable interest to identify HPV E6-and E7-derived CD41 T helper cell epitopes using overlapping peptide pools and to include them in peptide-based therapeutic vaccine design. [34][35][36][37][38] Our approach in the current study was to use computational HLA class II prediction algorithms to define HPV16-derived CD41 T cell epitopes, which bind promiscuously to the binding groove of multiple HLA-DR molecules. The minimal length to define HLA-class II restricted epitopes is 15 amino acids, thus we worked with 15-mer epitopes throughout the study.…”

“…Up to now, most studies focused on the identification of epitopes derived from the HPV oncoproteins E6 and E7, in the context of peptide-based immunotherapy against advanced lesions in patients. [34][35][36][37][38] To the best of our knowledge, there is only one study reporting CD41 T cell epitopes for HPV16 E2, 42 and no studies on E5-derived T helper epitopes. None of these studies deal with the identification of promiscuous CD41 T cell epitopes.…”

“…Most studies on identification of HPV-specific Th epitopes so far have been focusing on E6 and E7 as target antigens and overlapping peptide pools have been used rather than defined peptide epitopes (for review see Refs. [34][35][36][37][38]. Although successful, these approaches of systematic T cell epitope mapping are costly and time-consuming, as they require synthesis and several rounds of screening of peptides spanning the full length of the target antigen.…”

A Human Papillomavirus Type 16 E6 52-62 CD4 T-Cell Epitope Restricted by the HLA-DR11 Molecule Described in an Epitope Hotspot

“…4) [14]. One thousand T-cell clone cells were plated along with 1 × 10 5 alloegeneic LCL cells per well in duplicate.…”