四川彝族和新疆维族HLA-B位点基因多态性分析

应用PCR-SSP(Polymerase Chain Reaction-Sequence Specific Primer) 方法对无亲缘关系的106位四川彝族样品和110位新疆维族样品进行HLA-B基因分型。在彝族样品中共检出20个等位基因,其中高频率的等位基因为B*40（0.2028）、B*15（0.1604）、B*51(0.1274),低频率的等位基因为B*47 (0.0189)、B*27(0.0142)、B*44(0.0142)、B*18(0.0094)和B*78(0.0047)。在维族样品中共检出27个等位基因,其中高频率的等位基因为B*35 (0.1136)和B*51（0.1136）,低频率的等位基因为B*41（0.0045）、B*56（0.0045）和B*78（0.0091）。经χ2检验,两个民族群体的基因型分布均符合Hardy-Weinberg平衡。经遗传分析,四川彝族群体HLA-B基因座杂合度(H)、个体识别率(DP)和非父排除率(EP)分别为0.8977、0.9661和0.8009;维族群体的H、DP和EP分别为0.9372、0.9857和0.8732。本研究获得了四川彝族和新疆维族HL A-B基因座基因频率数据,为临床器官移植配型、人类学、法医学及疾病关联性研究提供了重要的群体遗传学资料。     

HLA-B*2736等位基因的序列分析

使用FLOW-SSO、PCR-SSP以及测序等分型技术, 发现一个与HLA-B*270401基因相关的未知基因。设计基因特异性引物单独扩增B*27基因的外显子2-5, 包括内含子2-4, 并进行双向测序, 分析与B*270401基因序列的差异。该基因的扩增产物为1 815 bp。与B*270401相比在外显子3和4共有10个碱基的改变, 从而使相应氨基酸发生错义或同义突变。碱基634 A→C (密码子130丝氨酸→精氨酸); 670 A→T (密码子142苏氨酸→丝氨酸); 683 G→T (密码子146色氨酸→亮氨酸); 698 A→T (密码子151谷氨酸→缬氨酸); 774 G→C (密码子176谷氨酸→天冬氨酸); 776 C→A (密码子177苏氨酸→赖氨酸); 781 C→G (密码子179谷氨酰胺→谷氨酸); 789 G→T (密码子181丙氨酸同义突变); 1 438 C→T (密码子206甘氨酸同义突变); 1 449 G→C (密码子210甘氨酸→丙氨酸)。在IMGT/HLA数据库中B*27组只有3个基因（B*270502 / 2706 / 2732）提交了内含子序列。该未知基因的内含子2序列与B*2706相同, 显示了与B*27组基因的同源性, 但其同源性在内含子3、4均未得到支持, 与B*27组基因相比, 内含子3的第106个碱基C→G, 碱基168缺失, 碱基179 G→A, 碱基536 G→A; 内含子4中碱基82 T→C。但其内含子3、4序列却与B*070201完全相同。该基因序列已提交GenBank, 编号为被DQ915176, 被WHO确认为HLA-B*2736等位基因。     

应用PCR-SSOP技术研究中国汉族、维吾尔族HLA-A基因座基因多态性

人类白细胞抗原（Human Leukocyte Antigen,HLA)基因复合物位于6p21.3,有220多个不同的功能基因,是人类基因组最复杂的遗传多态系统。HLA等位基因的变异在医学、法医学、人类学等领域具有重要的意义。自从1964年以来,HLA分型一直采用经典的微量淋巴细胞毒实验,但该方法是血清学水平的分,不能识别很多特异性的等位基因,而且高质量的抗体也不易获得。从20世纪90年代起,在国家自然科学基金的资助下,首先开展HLAⅡ类位点基因分研究及大规模群体多态性调查,所获得的中国主要民族基因数据已应用于多个领域。相比之下,HLAⅠ类基因数量更丰富,包含了A、B、C、E、F、G和假基因H、J、K、L等10个位点;基因分子结构更复杂,更具多态性。因此,HLAⅠ类DNA分型比HLAⅡ类分型及行多困难。直至目前中国人群HLA－A基因座基因多态性和分布频率的研究尚未充分进行。而任何DNA标记用于遗传分析、法医鉴定等领域之前,必须先进行群体调查,建立不同民族基因数据库,这是不可逾越的基础工作。鉴于此,采用灵敏而非同位素污染的PCR－SSOP基因分型技术,对165个汉族和162个维吾尔族个体的HLA－A基因座多态性进行调查。结果在汉族群体中发现22种等位基因,频率最高的是HLA－A＊1101（19．7％）,其次是＊201（12．72％）;在维族群体中发现22种等位基因,频率最高的是＊2407（17．90％）,等位基因＊0101、＊0201和＊3301的频率均大于10％;HLA－A＊0203、＊0205、＊0302、＊2403和＊3302仅在汉族群体中检出;HLA－A＊0205、＊0211、＊2301、＊2502、＊68012和＊6802仅在维族群体中检出。按照Hardy-Weinberg平衡定律检验,两个民族各等位基因型频率的预期值与实际观察值相吻合（P＞0．05）,证明了所获得汉族、维吾尔族HLA－A位点基因频率具有可靠性;同时也表明各等位基因的遗传特征符合符合孟德尔规律。经计算机统计分析,汉族群体HLA－A基因座杂合度（Heterozygosity,H)、个体识别率（Discrimination Power,DP)和非父排排率（Proba-bility of Paternity Exclusion,EPP)分别为0．9029、0．9776和0．8592;维族群体H、DP和EEP分别为0．9063、0．9379和0．7885。和其他遗传标记（如VNTR、STR、SNP）的单一位点相比,HLA－A具有高度的杂合率、个体识别率和非父排除率。因此,HLA－A等位基因在法医个体识别、亲权鉴定、基因诊断、人类学等领域具有重要的应用价值。     

Different evolutionary pathway of B*570101 and B*5801 (B17 group) alleles based in intron sequences

Two theories about MHC allele generation have been put forward: (1) point mutation diversification and/or (2) gene conversion events. A model supporting the existence of both of these mechanisms is shown in this paper; the possible evolution of the HLA-B*570101 and HLA-B*5801 alleles (which belong to the HLA-B17 serology group) is studied. The hypothesis favoured is that gene conversion events have originated these alleles, because intron sequences are also analysed. Evolution by point mutation should only be accepted if flanking introns have also been sequenced.The nucleotide sequence data (exons and introns) reported in this paper have been sequenced in our laboratory. They are in the GenBank nucleotide sequence database and have been assigned the accession numbers: B*150101—(a) exon 1, L79939; (b) exon 2 and exon 3, L48400; (c) intron 1, L76249; (d) intron 2, L42468; B*1515—(a) exon 1, exon 2 and exon 3, L49343; (b) intron 1 and intron 2, L76254; B*1539—(a) exon 2, AF033501; (b) exon 3, AF033502; (c) intron 1, AF034961; (d) intron 2 AF034962; B*350101—(a) exon 1, exon 2 and exon 3, L63544; (b) intron 1, L79921; (c) intron 2, L57505; B*510101—(a) exon 1, L77204; (b) exon 2 and exon 3, L47985; (c) intron 1, L76245; (d) intron 2, L42469; B*520102—(a) exon 1, L77205; (b) exon 2 and exon 3, L47984; (c) intron 1, L76244; (d) intron 2, L76251; B*5301—(a) exon 1, intron 1, exon 2, intron 2 and exon 3, U90566; B*1302—(a) intron 1, exon 2, intron 2, exon 3, AF196182; B*400101/02—(a) exon 2 and exon 3, L79937; (b) intron 1, L79919; (c) intron 2, L76629; B*4101—(a) intron 1, exon 2, intron 2 and exon 3, U90560; B*4102 (a) intron 1, exon 2, intron 2 and exon 3, AF 126199; B*4501—(a) intron 1, exon 2, intron 2 and exon 3, U90562; B*570101—(a) intron 1, exon 2, intron 2 and exon 3, AF196183; B*5801—(a) intron 1, exon 2, intron 2 and exon 3, AF196184All exon sequences were officially assigned as confirmatory by the WHO Nomenclature Committee in December 2003: B*1302, B*150101, B*350101, B*400101/02, B*4101, B*510101, B*570101, B*5801, B*5301, B*4501, B*520102, B*1515, B*4102 and B*1539. This follows the agreed policy that, subject to the conditions stated in the Nomenclature Report [Marsh et al. (2002) Tissue Antigens 60:407–464], names will be assigned to new sequences as they are identified. Lists of such new names will be published in the following WHO Nomenclature Report     

Position 45 influences the peptide binding motif of HLA-B*44:08

Position 45 represents a highly polymorphic residue within HLA class I alleles, which contacts the p2 position of bound peptides in 85% of the peptide–HLA structures analyzed, while the neighboring residues 41 and 46 are not involved in peptide binding. To investigate the influence of residue 45 at the functional level, we sequenced peptides eluted from recombinant HLA-B*44:08^{41Ala/45Met/46Ala} molecules and compared their features with known peptides from B*44:02^{41Thr/45Lys/46Glu}. While HLA-B*44:02 has an anchor motif of E at the p2 anchor position, HLA-B*44:08 exhibits Q and L as anchor motif. The 45^Met/Lys polymorphism contributes to the alteration in the peptide-binding motif and provides further evidence that mismatches at position 45 should be considered as nonpermissive in a transplantation setting.     

Human MHC class III genes, Bf and C4. Polymorphism, complotypes and association with MHC class I genes in the Finnish population

Electrophoretically detected genetic polymorphism of human MHC class III genes, factor B (Bf) and complement C4A and C4B, was studied in the Finnish population. Bf alleles were determined in a panel of sera from 70 unrelated individuals. The common Bf alleles, Bf*S and Bf*F, had frequencies of 73% and 26%, respectively. Only in 1 individual was another allele, Bf*F1, detected. The frequencies of the C4A and C4B alleles were based on studies of 254 unrelated individuals. In this panel, five different alleles were detected at the C4A locus and four at the C4B locus. At both loci an allele without a gene product, i.e. a 'null' allele, was observed with high frequency, 11% for C4A 'null' and 17% for C4B 'null'. The association of complotypes to HLA haplotypes was analyzed in 70 chromosomes. The most common combination, defined by class I and class III alleles, was HLA-B7-S31 (13%), followed by HLA-B35-F20 (8.4%) and HLA-B8-S03 (7.1%). Some HLA-B specificities, for example B15, B27 and B40, were associated with a variety of complotypes. The importance of complotyping in HLA genetics is discussed.     

内蒙古地区蒙古族HLA-A、B、DRB1基因座多态性分析

应用序列特异性寡核苷酸探针反向斑点杂交技术对内蒙古地区蒙古族106名无关健康个体的HLA-A、B和DRB1 基因座进行基因分型, 以研究内蒙古地区蒙古族人群HLA-A、B、DRB1基因座的等位基因及其组成的单倍型频率分布特征。 采用最大数学预期值算法计算HLA基因座的等位基因频率和单倍型频率。106 名内蒙古地区蒙古族个体的HLA-A、B、DRB1基因座分别检出13、29、13个等位基因。高频单倍型分别为 HLA-A*02-B*46 (0.0510); HLA-A*02-B*13(0.0495); HLA-A*02-B*51(0.0442); HLA-B*13-DRB1*07 (0.0555); HLA- B*46-DRB1*09(0.0378); HLA-B*35-DRB1*13(0.03300); HLA-A*02-B*13-DRB1*07(0.033019); HLA-A*02-B*46- DRB1*09(0.031985)。研究表明: 内蒙古地区蒙古族人群HLA基因座的等位基因和单倍型具有较高的遗传多态性。HLA- A*24-B*14, HLA-A*32-B*63在该民族具有极强的连锁不平衡。     

Sequence of a novel HLA-DQB1 allele

The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence data base and have been assigned the accesion number M74842. The name DQB1*0304 has been officially assigned by the WHO Nomenclature Committee in November 1991. This follows the agreed policy that, subject to the conditions stated in the most recent Nomenclature Report (WHO Nomenclature Committee for factors of the HLA system, 1991), names will be assigned to new sequences as they are identified. List of such new names will be published in the following WHO Nomenclature Report.     

中国新疆维族人群HLA-B等位基因与HIV-1感染易感性或抗性

通过对中国维吾尔族人群HLA-B等位基因的分布频率的研究,探讨HLA-B等位基因与HIV感染的易感 或抵抗性的相关性。本研究用PCR-SSP的方法对新疆维吾尔族110例无相关的健康对照者(HIV阴性)和128例 HIV阳性感染者进行HLA-B等位基因分型。用POPGEN软件对健康对照者人群进行Hardy-Weinberg平衡检 测,用卡方检验分析HLA-B等位基因在健康对照者和HIV阳性感染者频率分布的差异。在HIV-1阳性感染者 中,B*4901等位基因频率显著性增加(B*4901:P=0．02．OR=3．06,95%CI=1．16～8．10)。而在健埭对照者 中,B*40等位基因顿率增加具有统计意义(B*40:P=0．02．OR=0．39．95％CI=0．07～0．92)。由此可见,B* 4901等位基因可能与HIV-1感染的易感性有关,而B*40等位基因可能与与HIV-1感染的抵抗性有关。     

TCR alpha genes direct MHC restriction in the potent human T cell response to a class I-bound viral epitope

The underlying generic properties of alphabeta TCRs that control MHC restriction remain largely unresolved. To investigate MHC restriction, we have examined the CTL response to a viral epitope that binds promiscuously to two human leukocyte Ags (HLAs) that differ by a single amino acid at position 156. Individuals expressing either HLA-B*3501 (156Leucine) or HLA-B*3508 (156Arginine) showed a potent CTL response to the 407HPVGEADYFEY417 epitope from EBV. Interestingly, the response was characterized by highly restricted TCR beta-chain usage in both HLA-B*3501+ and HLA-B*3508+ individuals; however, this conserved TRBV9+ beta-chain was associated with distinct TCR alpha-chains depending upon the HLA-B*35 allele expressed by the virus-exposed host. Functional assays confirmed that TCR alpha-chain usage determined the HLA restriction of the CTLs. Structural studies revealed significant differences in the mobility of the peptide when bound to HLA-B*3501 or HLA-B*3508. In HLA-B*3501, the bulged section of the peptide was disordered, whereas in HLA-B*3508 the bulged epitope adopted an ordered conformation. Collectively, these data demonstrate not only that mobile MHC-bound peptides can be highly immunogenic but can also stimulate an extremely biased TCR repertoire. In addition, TCR alpha-chain usage is shown to play a critical role in controlling MHC restriction between closely related allomorphs.     

Residue 81 confers a restricted C-terminal peptide binding motif in HLA-B*44:09

Knowledge about the magnitude of individual polymorphism is a critical part in understanding the complexity of comprehensive mismatching. HLA-B*44:09 differs from the highly frequent HLA-B*44:02 allele by amino acid exchanges at residues 77, 80, 81, 82 and 83. We aimed to identify the magnitude of these mismatches on the features of HLA-B*44:09 bound peptides since residues 77, 80 and 81 comprise part of the F pocket which determines sequence specificity at the pΩ position of the peptide. Using soluble HLA technology we determined >200 individual (nonduplicate) self-peptides from HLA-B*44:09 and compared their features with that of the published peptide features of HLA-B*44:02. Both alleles illustrate an anchor motif of E at p2. In contrast to the C-terminal peptide binding motif of B*44:02 (W, F, Y or L), B*44:09-derived peptides are restricted predominantly to L or F. The source of peptides for both alleles is identical (LCL 721.221 cells) allowing us to identify 23 shared peptides. The majority of these peptides however contained the restricted B*44:09 anchor motif of F or L at the pΩ position. Molecular modelling based on the B*44:02 structure highlights that the differences of the C-terminal peptide anchor between both alleles can be explained primarily by the B*44:02(81Ala)?>?B*44:09(81Leu) polymorphism which restricts the size of the amino acid that can be accommodated in the F pocket of B*44:09. These results highlight that every amino acid substitution has an impact of certain magnitude on the alleles function and demonstrate how surrounding residues orchestrate peptide specificity.     

HIV Control through a Single Nucleotide on the HLA-B Locus

Genetic variation within the HLA-B locus has the strongest impact on HIV disease progression of any polymorphisms within the human genome. However, identifying the exact mechanism involved is complicated by several factors. HLA-Bw4 alleles provide ligands for NK cells and for CD8 T cells, and strong linkage disequilibrium between HLA class I alleles complicates the discrimination of individual HLA allelic effects from those of other HLA and non-HLA alleles on the same haplotype. Here, we exploit an experiment of nature involving two recently diverged HLA alleles, HLA-B*42:01 and HLA-B*42:02, which differ by only a single amino acid. Crucially, they occur primarily on identical HLA class I haplotypes and, as Bw6 alleles, do not act as NK cell ligands and are therefore largely unconfounded by other genetic factors. We show that in an outbred cohort (n = 2,093) of HIV C-clade-infected individuals, a single amino acid change at position 9 of the HLA-B molecule critically affects peptide binding and significantly alters the cytotoxic T lymphocyte (CTL) epitopes targeted, measured directly ex vivo by gamma interferon (IFN-γ) enzyme-linked immunospot (ELISPOT) assay (P = 2 × 10⁻¹⁰) and functionally through CTL escape mutation (P = 2 × 10⁻⁸). HLA-B*42:01, which presents multiple Gag epitopes, is associated with a 0.52 log₁₀ lower viral-load set point than HLA-B*42:02 (P = 0.02), which presents no p24 Gag epitopes. The magnitude of this effect from a single amino acid difference in the HLA-A*30:01/B*42/Cw*17:01 haplotype is equivalent to 75% of that of HLA-B*57:03, the most protective HLA class I allele in this population. This naturally controlled experiment represents perhaps the clearest demonstration of the direct impact of a particular HIV-specific CTL on disease control.     

A Molecular Basis for the Interplay between T Cells,Viral Mutants,and Human Leukocyte Antigen Micropolymorphism

Mutations within T cell epitopes represent a common mechanism of viral escape from the host protective immune response. The diverse T cell repertoire and the extensive human leukocyte antigen (HLA) polymorphism across populations is the evolutionary response to viral mutation. However, the molecular basis underpinning the interplay between HLA polymorphism, the T cell repertoire, and viral escape is unclear. Here we investigate the T cell response to a HLA-B*35:01- and HLA-B*35:08-restricted ⁴⁰⁷HPVGEADYFEY⁴¹⁷ epitope from Epstein-Barr virus and naturally occurring variants at positions 4 and 5 thereof. Each viral variant differently impacted on the epitope''s flexibility and conformation when bound to HLA-B*35:08 or HLA-B*35:01. We provide a molecular basis for understanding how the single residue polymorphism that discriminates between HLA-B*35:01/08 profoundly impacts on T cell receptor recognition. Surprisingly, one viral variant (P5-Glu to P5-Asp) effectively changed restriction preference from HLA-B*35:01 to HLA-B*35:08. Collectively, our study portrays the interplay between the T cell response, viral escape, and HLA polymorphism, whereby HLA polymorphism enables altered presentation of epitopes from different strains of Epstein-Barr virus.     

Mutually exclusive T-cell receptor induction and differential susceptibility to human immunodeficiency virus type 1 mutational escape associated with a two-amino-acid difference between HLA class I subtypes

The relative contributions of HLA alleles and T-cell receptors (TCRs) to the prevention of mutational viral escape are unclear. Here, we examined human immunodeficiency virus type 1 (HIV-1)-specific CD8(+) T-cell responses restricted by two closely related HLA class I alleles, B*5701 and B*5703, that differ by two amino acids but are both associated with a dominant response to the same HIV-1 Gag epitope KF11 (KAFSPEVIPMF). When this epitope is presented by HLA-B*5701, it induces a TCR repertoire that is highly conserved among individuals, cross-recognizes viral epitope variants, and is rarely associated with mutational escape. In contrast, KF11 presented by HLA-B*5703 induces an entirely different, more heterogeneous TCR beta-chain repertoire that fails to recognize specific KF11 escape variants which frequently arise in clade C-infected HLA-B*5703(+) individuals. These data show the influence of HLA allele subtypes on TCR selection and indicate that extensive TCR diversity is not a prerequisite to prevention of allowable viral mutations.     

HLA and non-HLA genes in Beh?et’s disease: a multicentric study in the Spanish population

Introduction

According to genome wide association (GWA) studies as well as candidate gene approaches, Behçet’s disease (BD) is associated with human leukocyte antigen (HLA)-A and HLA-B gene regions. The HLA-B51 has been consistently associated with the disease, but the role of other HLA class I molecules remains controversial. Recently, variants in non-HLA genes have also been associated with BD. The aims of this study were to further investigate the influence of the HLA region in BD and to explore the relationship with non-HLA genes recently described to be associated in other populations.

Methods

This study included 304 BD patients and 313 ethnically matched controls. HLA-A and HLA-B low resolution typing was carried out by PCR-SSOP Luminex. Eleven tag single nucleotide polymorphisms (SNPs) located outside of the HLA-region, previously described associated with the disease in GWA studies and having a minor allele frequency in Caucasians greater than 0.15 were genotyped using TaqMan assays. Phenotypic and genotypic frequencies were estimated by direct counting and distributions were compared using the χ² test.

Results

In addition to HLA-B*51, HLA-B*57 was found as a risk factor in BD, whereas, B*35 was found to be protective. Other HLA-A and B specificities were suggestive of association with the disease as risk (A*02 and A*24) or protective factors (A*03 and B*58). Regarding the non-HLA genes, the three SNPs located in IL23R and one of the SNPs in IL10 were found to be significantly associated with susceptibility to BD in our population.

Conclusion

Different HLA specificities are associated with Behçet’s disease in addition to B*51. Other non-HLA genes, such as IL23R and IL-10, play a role in the susceptibility to the disease.     

HLA-Cw*04 and hepatitis C virus persistence

In studies of acute hepatitis C virus (HCV) infection, the early host immune response is one of the determinants of viral persistence. The class I human leukocyte antigens (HLA), which present foreign antigen to cytolytic T cells, are integral components of this response. We hypothesized that the highly polymorphic HLA genes affect the outcome of an HCV infection. To test this hypothesis, we molecularly typed 231 persons with well-documented clearance of an HCV infection and 444 matched persistently infected persons. HLA-A*1101 (odds ratio [OR], 0.49; 95% confidence interval [95% CI], 0.27 to 0.89), HLA-B*57 (OR, 0.62; 95% CI, 0.39 to 1.00), and HLA-Cw*0102 (OR, 0.43; 95% CI, 0.21 to 0.89) were associated with viral clearance, whereas HLA-A*2301 (OR, 1.78; 95% CI, 1.01 to 3.11) and HLA-Cw*04 (OR, 1.78; 95% CI, 1.21 to 2.59) were associated with viral persistence. HLA-Cw*04 is in strong linkage disequilibrium with HLA-B*53 and HLA-B*35, but only HLA-B*53 (OR, 1.70; 95% CI, 0.95 to 3.06) and the Cw*04-B*53 haplotype (OR, 1.76; 95% CI, 0.94 to 3.26) were weakly associated with viral persistence. HLA-B*53 has similar, but not necessarily identical, binding specificity to some HLA-B*35 subtypes (B*35-Px group). The association with the B*35-Px group was less strong than with HLA-B*53 alone. The association of HLA-Cw*04 with HCV persistence was codominant (two copies of the gene were more strongly associated with persistence than one copy). However, HLA-Cw*04 was not associated with HCV RNA levels among the persistently infected individuals. Since Cw*04 is a ligand for the killer immunoglobulin-like receptors on natural killer cells, these cells may be involved in recovery from HCV infection. Further investigation is needed to understand the relationship between class I alleles and HCV clearance.     

Molecular Dynamics Simulation Reveals the Selective Binding of Human Leukocyte Antigen Alleles Associated with Beh?et's Disease

Behçet’s disease (BD), a multi-organ inflammatory disorder, is associated with the presence of the human leukocyte antigen (HLA) HLA-B*51 allele in many ethnic groups. The possible antigen involvement of the major histocompatibility complex class I chain related gene A transmembrane (MICA-TM) nonapeptide (AAAAAIFVI) has been reported in BD symptomatic patients. This peptide has also been detected in HLA-A*26:01 positive patients. To investigate the link of BD with these two specific HLA alleles, molecular dynamics (MD) simulations were applied on the MICA-TM nonapeptide binding to the two BD-associated HLA alleles in comparison with the two non-BD-associated HLA alleles (B*35:01 and A*11:01). The MD simulations were applied on the four HLA/MICA-TM peptide complexes in aqueous solution. As a result, stabilization for the incoming MICA-TM was found to be predominantly contributed from van der Waals interactions. The P2/P3 residue close to the N-terminal and the P9 residue at the C-terminal of the MICA-TM nonapeptide served as the anchor for the peptide accommodated at the binding groove of the BD associated HLAs. The MM/PBSA free energy calculation predicted a stronger binding of the HLA/peptide complexes for the BD-associated HLA alleles than for the non-BD-associated ones, with a ranked binding strength of B*51:01 > B*35:01 and A*26:01 > A*11:01. Thus, the HLAs associated with BD pathogenesis expose the binding efficiency with the MICA-TM nonapeptide tighter than the non-associated HLA alleles. In addition, the residues 70, 73, 99, 146, 147 and 159 of the two BD-associated HLAs provided the conserved interaction for the MICA-TM peptide binding.     

High Resolution Human Leukocyte Antigen Class I Allele Frequencies and HIV-1 Infection Associations in Chinese Han and Uyghur Cohorts

Background

Host immunogenetic factors such as HLA class I polymorphism are important to HIV-1 infection risk and AIDS progression. Previous studies using high-resolution HLA class I profile data of Chinese populations appeared insufficient to provide information for HIV-1 vaccine development and clinical trial design. Here we reported HLA class I association with HIV-1 susceptibility in a Chinese Han and a Chinese Uyghur cohort.

Methodology/Principal Findings

Our cohort included 327 Han and 161 Uyghur ethnic individuals. Each cohort included HIV-1 seropositive and HIV-1 seronegative subjects. Four-digit HLA class I typing was performed by sequencing-based typing and high-resolution PCR-sequence specific primer. We compared the HLA class I allele and inferred haplotype frequencies between HIV-1 seropositive and seronegative groups. A neighbor-joining tree between our cohorts and other populations was constructed based on allele frequencies of HLA-A and HLA-B loci. We identified 58 HLA-A, 75 HLA-B, and 32 HLA-Cw distinct alleles from our cohort and no novel alleles. The frequency of HLA-B*5201 and A*0301 was significantly higher in the Han HIV-1 negative group. The frequency of HLA-B*5101 was significantly higher in the Uyghur HIV-1 negative group. We observed statistically significant increases in expectation-maximization (EM) algorithm predicted haplotype frequencies of HLA-A*0201-B*5101 in the Uyghur HIV-1 negative group, and of Cw*0304-B*4001 in the Han HIV-1 negative group. The B62s supertype frequency was found to be significantly higher in the Han HIV-1 negative group than in the Han HIV-1 positive group.

Conclusions

At the four-digit level, several HLA class I alleles and haplotypes were associated with lower HIV-1 susceptibility. Homogeneity of HLA class I and Bw4/Bw6 heterozygosity were not associated with HIV-1 susceptibility in our cohort. These observations contribute to the Chinese HLA database and could prove useful in the development of HIV-1 vaccine candidates.     

Amino acid 95 causes strong alteration of peptide position PΩ in HLA-B*41 variants

There have been several attempts over the years to identify positions in the peptide-binding region (PBR) of human leukocyte antigens (HLA) that influence the specificity of bound amino acids (AAs) at each position in the peptide. Originally, six pockets (A-F) were defined by calculating the surface area of the PBR on the crystal structure of HLA-A2 molecules. More recent crystallographic analyses of a variety of HLA alleles have led to broader pocket definitions. In this study, we examined the peptide-binding specificity of HLA-B*41 alleles and compared our results with the available pocket definitions. By generating recombinant HLA-B molecules and studying the eluted peptides by mass spectrometry and pool sequencing, we detected two different POmega peptide motifs within the B*41 group: Leu vs Val/Pro. Specificity was dependent on the presence of Leu (B*4102, B*4103, and B*4104) vs Trp (B*4101, B*4105, and B*4106) at AA position 95 in the HLA molecule, whose impact on POmega has been a subject of controversy in current pocket definitions. In contrast, the Arg97Ser mutation did not affect pocket F binding specificity in B*41 subtypes although residue 97 was previously identified as a modulator of peptide binding for several HLA class I alleles. According to most pocket definitions, this study shows that the Asn80Lys substitution in B*4105 impels the peptide's POmega anchor toward more promiscuity. Our sequencing results of peptides eluted from HLA-B*41 variants demonstrate the limitations of current pocket definitions and underline the need for an extended peptide motif database for improved understanding of peptide-major histocompatibility complex interactions.