Cytotoxic T-cell recognition of HIV-1 cross-clade and clade-specific epitopes in HIV-1-infected Thai and Japanese patients.

OBJECTIVE To identify and characterize cytotoxic T-cell (CTL) epitopes for HIV-1 clade E using eight known HLA-A*1101-restricted HIV-1 clade B epitopes. METHODS Induction of clade E-specific CTL was examined by stimulating peripheral blood mononuclear cells (PBMC) from clade E-infected Thai individuals with the clade E-specific peptide corresponding to the clade B epitopes. Cross-clade and clade-specific CTL recognition for these epitopes was analysed using CTL clones and bulk CTL specific for these epitopes. To clarify the presentation of these epitopes in HIV-1-infected T cells, CTL recognition for the clade E-specific and cross-clade epitopes was investigated using CD4CXCR4 cells infected with an HIV-1 clade E clone. RESULTS Three epitopes, which are identical among clades A-E, were recognized as cross-clade CTL epitopes in both individuals. Clade B and E sequences corresponding to three epitopes were recognized as clade-specific epitopes in clade B-infected and clade E-infected individuals, respectively. In contrast, clade E-specific peptides corresponding to two other clade B epitopes failed to elicit clade E-specific CTL. CTL specific for the three cross-clade and three clade E-specific epitopes effectively lysed target cells infected with HIV-1 clade E virus. CONCLUSIONS These six epitopes are found to be processed naturally in HIV-1 clade E-infected cells. We show here that a strategy utilizing HIV-1 clade B epitopes is very useful for identifying clade E CTL epitopes.