Engineering immunogenic consensus T helper epitopes for a cross-clade HIV vaccine

Methods. 2004 Dec;34(4):476-87. doi: 10.1016/j.ymeth.2004.06.003.

Abstract

Developing a vaccine that will stimulate broad HIV-specific T cell responses is difficult because of the variability in HIV T cell epitope sequences, which is in turn due to the high mutation rate and consequent strain diversity of HIV-1. We used a new Class II version of the EpiMatrix T cell epitope-mapping tool and Conservatrix to select highly conserved and promiscuous Class II HLA-restricted T cell epitopes from a database of 18,313 HIV-1 env sequences. Criteria for selection were: (1) number of HIV-1 strains represented as measured by Conservatrix; (2) EpiMatrix score; and (3) promiscuity (number of unique MHC motifs contained in the peptide). Using another vaccine design tool called the EpiAssembler, a new set of overlapping, conserved and immunogenic HIV-1 peptides were engineered creating extended "immunogenic consensus" sequences. Each overlapping 9-mer of the 20-23 amino acid long immunogenic consensus peptides was conserved in a large number (range 893-2254) of individual HIV-1 strains, although the novel peptides were not representative of any single strain of HIV. We synthesized nine representative peptides. T helper cell responses to the peptides were evaluated by ELISpot (gamma-interferon) assay, using peripheral blood monocytes (PBMC) obtained from 34 healthy long term non-progressor (LT) or moderate-progressor (MP) donors (median years infected = 8.88, median CD4 T cells = 595, median VL = 1044). Nine peptides were tested, of which eight were confirmed in ELISpot assays using PBMC from the LT/MP subjects. These epitopes were ranked by Conservation and EpiMatrix score 1, 2, 3, 5, 7, 11, and 14 out of the set of 9 original peptides. Five of these peptides were selected for inclusion in an epitope-driven cross-clade HIV-1 vaccine (the GAIA vaccine). These data confirm the utility of bioinformatics tools to select and construct novel "immunogenic consensus sequence" T cell epitopes for a globally relevant vaccine against HIV.

Publication types

  • Comparative Study

MeSH terms

  • AIDS Vaccines / genetics*
  • AIDS Vaccines / immunology
  • Algorithms
  • Amino Acid Sequence
  • Cohort Studies
  • Consensus Sequence*
  • Epitope Mapping / methods*
  • Epitopes, T-Lymphocyte / genetics*
  • Epitopes, T-Lymphocyte / immunology
  • HIV-1 / genetics*
  • HIV-1 / immunology
  • Humans
  • Molecular Sequence Data
  • Peptides / chemical synthesis
  • Pilot Projects
  • Sequence Analysis, Protein / methods
  • T-Lymphocytes, Helper-Inducer / immunology*
  • T-Lymphocytes, Helper-Inducer / metabolism*

Substances

  • AIDS Vaccines
  • Epitopes, T-Lymphocyte
  • Peptides