View All Abstracts for Session 56
290 Identification and Optimization of HIV-Specific CTL Antigens for Vaccine Design
C. Boggiano*1, C. Pinilla1, B. D. Walker2, and S. E. Blondelle1
1Torrey Pines Inst. for Molecular Studies, San Diego, CA, USA and 2Partners AIDS Res. Ctr., Harvard Med. Sch., Charlestown, MA, USA
Background: Despite the great advances in antiviral therapy for HIV infection, a successful global intervention for prevention and treatment will require an effective vaccine. Our approach toward the development of an HIV vaccine is based on the optimization and identification of T-cell epitopes that will stimulate CD8+ cytotoxic T-lymphocyte (CTL) responses. Synthetic combinatorial libraries (SCLs) were used to identify and optimize such peptide ligands.
Methods: Nonapeptide positional scanning SCLs were screened for their ability to stimulate cytolytic activity by T-cell clones isolated from HIV seropositive patients, having specificity for epitopes of different HIV proteins (e.g., GAG, RT, TAT, etc.). The amino acids corresponding to the most active mixtures for each position were selected for synthesis of individual peptides and then tested on the same and different clones specific for the original HIV peptide. In a second approach, the screening results were used to score and rank all overlapping nonapeptides in all of the viral proteins of the GenPept database using a biometrical analysis, and predict the most stimulatory natural peptides for a given T-cell clone.
Results: Notably, the majority of the 9 amino acids defining the most active mixtures corresponded to residues of the native peptide epitopes. A number of superagonists (EC50 10- to 100-fold greater than the original epitope) were identified from direct deconvolution of the library. In addition, the biometrical analysis allowed the identification of the original epitope as well as of natural stimulatory analogs (double or triple substitution) of this epitope that derive from the same HIV-1 protein but different isolates, within the peptides having the highest scores and ranks.
Conclusions: These studies demonstrate the utility of combinatorial peptide libraries in the rapid identification and optimization of TCR peptide ligands and thus provide an important strategy for the development and design of vaccines for the immunotherapeutic treatment of HIV infection.
Contact Author about this Abstract
