AEGiS-15IAC: Novel HLA-A2 and HLA A24-restricted subtype A/E Vif and Vpr CTL Epitope identified in HIV-1 infected Thai Patients.

15th International AIDS Conference

Bangkok, Thailand - July 11-16, 2004

Novel HLA-A2 and HLA A24-restricted subtype A/E Vif and Vpr CTL Epitope identified in HIV-1 infected Thai Patients.

Int Conf AIDS 2004 Jul 11-16; 15:(abstract no. A10340)

Buranapraditkun S, Hansasuta P, Rowland-Jones S, Phanuphak P, Ruxrungtham K
Chulalongkorn University, Bangkok, Thailand

BACKGROUND: Little data had been made on CTL responses against subtype A/E HIV-1 regulatory proteins. In addition, the HLA polymorphism among Thais is also remarkably different from the western cohorts. Our previous studies showed various frequency of CTL responses to A/E HIV-1 regulatory proteins: nef, vpr, tat, vif, rev, vpu was 93, 46, 46, 39, 36, and 21%, respectively. Interestingly, among those, 25 possible novel epitopes observed in 15 patients. This study has further characterized some of these epitopes.

METHOD: CTL responses and epitope mapping were performed by IFN-γ ELSPOT assay and HLA restriction were performed by classical Cr-51 release assay. HIV-1 subtype A/E truncated short peptides (12-13 a.a in length) of Vif residues 94-112 (YSTQIDPDLADRLIHLQYF) and Vpr residues 27-45 (KNEAVRHFPRPWLHGLGQY) were used further to characterize these 2 novel epitopes. HLA class I was analyzed by genotyping. The positive cut-off of ELISPOT was 100 SFU/106 PBMCs and 2 folds higher than the background.

RESULTS: In the HLA-restriction study, 3 patients were analyzed. Each Epitope of Vif and Vpr were found to be restricting by HLA A2 and A24, respectively. Two HLA A2 patients (A2 and A0206), who have CTL response to "YSTQIDPDLADRLIHLQYF" Vif A/E peptide, were tested with 3 truncated shorter peptides (12-13 aa in length) using IFN-γ ELISPOT assay. One of them recognized a 12 aa. "YSTQIDPDLADR" and the other with recognized a 13 aa "QIDPDLADRLIHL" HIV A/E Vif peptide. A patient was HLA A24, who has CTL response to "KNEAVRHFPRPWLHGLGQY" Vpr A/E peptide, was tested with 3 truncated shorter peptides (12-13 aa in length) using IFN-γ ELISPOT assay. The patient recognized a 13 aa. "AVRHFPRPWLHGL" HIV A/E Vpr peptide. Discussion: New HLA A2 and HLA A24 restricted subtype A/E Vif and Vpu epitope of 12-13 aa., were identified. Further fine mappings and peptide titration assays are ongoing. The roles of these new epitopes in HIV pathogenesis and vaccine development are unknown and need further investigation.

Keywords: AEGIS, HLA-A2 Antigen, HLA-A Antigens, HIV-1, Epitopes, Acquired Immunodeficiency Syndrome, Epitope Mapping, Peptides, HLA-A24, Humans, immunology

040711
A10340