8th Conference on Retroviruses and Opportunistic Infections Chicago, IL - February 4 - 8, 2001

Conf Retroviruses Opportunistic Infect 2001 Feb 4-8; 8:51 (abstract no. 30)

K. Ruxrungtham^1,2, S. Buranapraditkul^1,2, P. Hansasutha^1,3, S. Rowland-Jones³, S. Sirivichaykul^1,2, P. Warachit⁴, M. Honda⁵, and P. Phanuphak^1
1Chulalongkorn Univ., Bangkok, Thailand; ²Thai Red Cross AIDS Res. Ctr., Bangkok, Thailand; ³Inst. of Molecular Med., John Radcliffe Hosp., Oxford, UK; ⁴Dept. of Med. Sci., Thailand; and ⁵Natl. Inst. of Infectious Diseases, Tokyo, Japan.

BACKGROUND: Our previous study, using a Cr⁵¹ release classic CTL assay, has shown that HIV-1 gag is the most common antigen recognized by >90% of Thai patients infected by HIV-1 clade A/E. In addition, HIV-1 gag has a very high rate of cross-clade CTL activity between clade A and B among clade A/E infected Thai patients. The HLA polymorphism among Thais is also remarkably different from the western cohorts. It is warranted to further study HIV gag epitope mapping in HIV-infected Thai patients.

METHODS: Both the CTL epitope mapping and HLA restriction were performed by a Cr⁵¹ release classic CTL assay. HIV-1 clade A gag truncated peptides (aa 1-499, consensus sequence of 92UG037; each is 20 aa in length, with 10-aa overlaps between sequential peptides) were used for gag-CTL epitope mapping (kindly provided from NIH AIDS Research and Reference Reagent Program, US). HLA class I was analyzed by genotyping.

RESULTS: Ten patients (mean CD4 count 535 cells/mm³ median plasma HIV-RNA 7502 copies/ml) with gag-specific CTL were studies for epitope mapping. 14 gag- specific epitopes were identified: 7 in p17 and the other 7 in p24 region. Of note, 40% of the patients recognized the same epitope: p24 peptide 275-282. In the HLA restriction study, A2 (p24, 141-160), A26 (p24, 167-175), B7 (p24, 181-191), and C1 (p24, 275-282, 4 cases) restriction gag epitopes were identified. Interestingly, the C1 or Cw1 restricted gag epitope is the most common epitope found in this cohort and has not been reported in the literature.

CONCLUSIONS: Fourteen HIV-1 gag-specific epitopes were identified among 10 patients infected with clade A/E. P24 epitope 272-282 with C1 or Cw1 restriction is the most common epitope found in this cohort. Further study is required in a larger sample size to find the common and immunodominant epitopes among Thai patients.

2001-02-04
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