HCV genotype 1a representative sequence elicits broad CD8+ T cell responses (113.10)

Abstract

Abstract Vaccines designed to prevent or to treat hepatitis C viral infection must achieve maximum cross-reactivity against widely divergent circulating strains. Computer-generated sequences minimize genetic distance between circulating strains, and can be generated as a consensus sequence (most common amino acid at each position) or a representative sequence (derived with Bayesian and maximal likelihood phylogenetic tools). Broad recognition of such sequences in HCV has not been demonstrated. Consensus and representative sequences were generated from 390 full-length HCV genotype 1a polypeptide sequences. Sequence mutations in known epitopes were identified by longitudinal sequencing of HCV-infected subjects. Peptides encoding consensus, representative, and variant epitope sequences were tested for the capacity to expand CD8 T cells from HCV-infected subjects and to elicit cross-reactive responses by IFNg ELISpot. The representative and consensus sequences were identical for 9/11 epitopes examined. T cell lines generated against representative sequence peptides were generally cross-reactive to consensus sequence and natural sequence variants. Furthermore, representative sequence peptides generated more robust T cell responses than did natural sequence variant peptides. The broadest recognition of highly diverse circulating HCV strains was achieved using CD8+ T cells expanded with representative sequence HCV. These data support the use of representative sequence in HCV vaccine design.