AEGiS-11IAC: Identification of an A3 family supermotif epitope in HIV-1.

11th International AIDS Conference

Vancouver, British Columbia — July 7-12, 1996

Identification of an A3 family supermotif epitope in HIV-1.

Int Conf AIDS 1996 Jul 7-12; 11:23 (abstract no. LB.A.6007)
Threlkeld SC, Kalams SA, Sette A, Johnson RP, Wilkes B, Ruhle D, Walker BD; MGH, Charlestown, MA. Fax: (617) 726-5411. E-mail: THRELKELDS@Al.mgh.harvard.edu.

OBJECTIVE: To define CTL epitopes in HIV-1 which can be presented by multiple alleles in the HLA A3 superfamily (HLA3, A11, A31, A68).

METHODS: Limiting dilution cloning of CD8 cells was performed in HIV-1 infected persons expressing either HLA A3 or A11. HIV-1 specific CTL clones restricted by HLA A3 and A11 were identified and fine mapped using synthetic HIV-1 peptides at limiting peptide concentrations. The effects of alanine substitutions as well as natural sequence variants on epitope recognition were determined. Quantitative MHC-peptide binding assays were performed using (125)I radiolabelled peptides.

RESULTS: A nine amino acid epitope in HIV-1 RT (AIFQSSMTK) was identified which was recognized by HLA A3 and A11 restricted CTL clones from different individuals. This peptide could be shown in binding assays to bind to both HLA A3 and A11. Both the A3-restricted and A11-restricted clones were able to recognize naturally processed peptides, and peptide titration studies revealed that half-maximal lysis was achieved at equivalent peptide concentrations of approximately 10 ng/ml. The effects of sequence variation and alanine substitutions on recognition will be presented.

CONCLUSIONS: We have established the existence of an A3 superfamily motif in HIV-1 RT. The characterization of such supermotifs may be important in generating peptide-based vaccines. Incorporation of such epitopes which are presented by multiple antigens within an HLA superfamily would allow construction of peptide-based vaccines which would be more widely effective in outbred populations.

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LBA6007