Objective: To identify protective human leukocyte antigen (HLA) alleles in an HIV-infected south-east Asian population, in whom HLA-B*57 prevalence is lower than other ethnic groups, and HIV-1 CRF01_AE is the dominant circulating subtype.
Design: Cross-sectional study of Thai patients with chronic HIV infection.
Methods: Five hundred and fifty-seven HIV-1 CRF01_AE-infected Thais were recruited. Their HLA type and viral load were determined to statistically analyze the association of each allele in viral control. In-silico molecular dynamics was also used to evaluate the effect of HLA structure variants on epitope binding.
Results: HLA-B*35:05 was identified as the most protective allele (P = 0.003, q = 0.17), along with HLA-B*57:01 (P = 0.044, q = 0.31). Structurally, HLA-B*35:05 belonged to the HLA-B*35-PY group of HLA-B*35 alleles; however, unlike the other HLA-B*35 alleles that carry Arg (R) at residue 97, it has unique sequences at T94, L95, and S97, located within the peptide-binding groove. Analysis of the three-dimensional HLA structure and molecular dynamics indicates that S97 in HLA-B*35:05 leads to less flexibility in the groove, and shorter distances between the α-helixes compared with the disease-susceptible HLA-B*35-PY allele, HLA-B*35:01.
Conclusion: These data indicate the existence of a protective effect of HLA-B*57 across ethnic groups and highlight HLA-B*35:05 as an allele uniquely protective in subtype CRF01_AE-infected Thais. The divergence of HLA-B*35:05 from conventional HLA-B*35-PY structural sequences at the peptide-binding groove is consistent with previous studies that have identified HLA residue 97 as strongly influential in shaping HLA impact on immune control of HIV, and that a more restricted peptide-binding motif may be associated with improved control.
Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Sakamoto, Nagasaki City, Nagasaki, Japan.
Correspondence to Koya Ariyoshi, MD, PhD, Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, 1-12-4, Sakamoto, Nagasaki City, Nagasaki 852-8523, Japan. Tel: +81 95 8197842; fax: +81 95 8197843; e-mail: email@example.com
Received 23 August, 2013
Revised 7 January, 2014
Accepted 7 January, 2014
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