- Poster presentation
- Open Access
Sequence based typing of HLA-A and B Exons-2 and -3 in a HIV-positive native community with limited HLA diversity from the North of Argentina
© Dilernia et al; licensee BioMed Central Ltd. 2012
- Published: 13 September 2012
- Native Community
- Typing Study
- Specific Allele
- Peptide Specificity
- Restricted Diversity
We previously reported a limited diversity of HLA-class I alleles in two-digits typing studies of HIV-positive native populations from Oran, North of Argentina. In the present study we determine whether the restricted diversity observed at low-resolution reflects also a restricted genetic diversity in HLA peptide groove.
We studied 65 HIV-positive patients whose HLA-A and -B genes were previously typed by SSOP technique. We set-up a sequence-based typing of the most prevalent alleles in Oran. HLA-A and B were initially PCR-amplified and exons-2 and -3 were sequenced. NCBI-SBT-Interpretation tool was used to confirm the two-digits typing with previous SSOP data. We designed a set of primers specifics for HLAs highly prevalent in Oran to achieve differential PCR-amplification of each allele in heterozygote patients. Phylogenetic analysis was used to assign exons-2 and -3 sequences to a high-resolution HLA group.
Our results show that for HLA-A alleles, 85.1% of A*02 are A*02:01:01:01, 96.7% of A*31 are A*31:01:02 and 92.8% of A*24 are A*24:02:01:01. In the case of A*68, 50% are A*68:01:02 and 31.2% are A*68:17. For HLA-B alleles, B*35 was diverse: B*35:01:01:01 (15.8%), B*35:04:01 (15.8%), B*35:05:01 (21.1%) and B*35:19 (21.1%). 43.8% of B*39-alleles were B*39:05:01 and 25% were B*39:03. 52.9% of B*48-alleles were B*48:01:01 and 35.3% were B*48:03:01. 62.5% of B*51 alleles were B*51:01:01. The mentioned alleles represent the 73.1% of HLA-A genetic diversity and the 45.4% of HLA-B. All the polimorphisms observed lead to non-synonymous changes.
Our results show that two-digits typing of HLA-A usually corresponds with a specific allele in our population. For HLA-B alleles, observed within-subtype diversity was higher. The different protein sequence encoded by exons-2 and -3 may lead to different peptide specificities among alleles from the same HLA-B subtype that would be miss-classified as homogeneous in a low-resolution typing study.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.