Design, Expression, and Processing of Epitomized Hepatitis C Virus-Encoded CTL Epitopes

Abstract

Hepatitis C virus (HCV) vaccine efficacy may crucially depend on immunogen length and coverage of viral sequence diversity. However, covering a considerable proportion of the circulating viral sequence variants would likely require long immunogens, which for the conserved portions of the viral genome, would contain unnecessarily redundant sequence information. In this study, we present the design and in vitro performance analysis of a novel “epitome” approach that compresses frequent immune targets of the cellular immune response against HCV into a shorter immunogen sequence. Compression of immunological information is achieved by partial overlapping shared sequence motifs between individual epitopes. At the same time, sequence diversity coverage is provided by taking advantage of emerging cross-reactivity patterns among epitope variants so that epitope variants associated with the broadest variant cross-recognition are preferentially included. The processing and presentation analysis of specific epitopes included in such a compressed, in vitro-expressed HCV epitome indicated effective processing of a majority of tested epitopes, although re-presentation of some epitopes may require refined sequence design. Together, the present study establishes the epitome approach as a potential powerful tool for vaccine immunogen design, especially suitable for the induction of cellular immune responses against highly variable pathogens.

HLA and Infectious Diseases

“…Given the extent of HLA polymorphism and the (177) and vaccinating individuals only with epitopes against which they mount a CTL response ("personalized peptide vaccination") (178), suggest that further developments in vaccine design are likely in this rapidly evolving field.…”

Lessons learned from natural infection: focusing on the design of protective T cell vaccines for HIV/AIDS

“…(a) Mosaic vaccine, three or four valent full-length constructs that maintain colinearity by in silico recombination of natural protein sequences [5] (b) Center of tree (COT) + approach, includes one full-length, nearoptimum COT sequence based upon the maximum likelihood phylogenetic tree plus optimized peptide fragment sets for each protein [4] (c) Epitome approach to compress cross-reactive variant sequences into shorter immunogen lengths [110] Allele-based escape-reversion epitope vaccine constructs Epitope enhancement by sequence modification Multi-epitope/minigene CD4 + and CD8 + T cell vaccine constructs and multi-site delivery strategies [84] Single chain trimer (SCT) CD8 + CTL vaccine constructs In vivo DNA electroporation Multiple heterologous prime boost strategies [111][112][113][114] Mucosal delivery strategies combined to empower systemic immunization and establish mucosal T cell effector and central memory [111] Inclusion of synergistic combinations of Toll-like receptors (TLRs), tumor necrosis factor receptor superfamily (TNFRSF), and costimulatory molecules (CD40L, 41BBL, OX40L, CD70) optimizing tissue-resident T effector memory and T central memory cells Counteract negative regulators (IL-10) and co-inhibitory receptors (CTLA-4, PD1, BTLA) that dampen the immune response [115] Push-Pull approaches combining molecular adjuvants and costimulatory molecules with blockage of T regulatory functions to maximize vaccine efficacy [116] Review Trends in Immunology Vol.31 No.3…”

Translation of HLA–HIV Associations to the Cellular Level: HIV Adapts To Inflate CD8 T Cell Responses against Nef and HLA-Adapted Variant Epitopes

“…Furthermore, presence of escape mutations in a vaccine immunogen may influence the immunodominance of vaccine-induced CTL responses, as suggested by significant changes in immunodominance hierarchies that follow early viral evolution and diversification in natural infection (6). Understanding the immunological consequences of specific HIV variations may become increasingly important as more are incorporated into polyvalent vaccines designed to optimise population diversity coverage (1, 7, 8). …”