HLA-A*0201-BSP融合基因的构建与原核表达

克隆表达可生物素化的HLA-A＊0201的重链胞外区是制备HLA-A＊0201-肽四聚体的先决条件。本研究构建重组HLA-A＊0201-BSP融合基因的表达载体，以制备HLA—A2四聚体。根据已报道的序列设计特异引物，利用逆转录聚合酶链反应（RT-PCR）方法从已鉴定为HLA—A＊0201基因型的健康人白细胞中克隆HLA—A＊0201重链胞外区的基因．拼接上依赖生物素-蛋白连接酶（biotin-protein ligase，BirA）的可生物素化序列（BirA substrate peptide．BSP），构建HLA—A＊0201-BSP的原核表达载体，在大肠杆菌DH50t中进行表达。结果表明：成功扩增出HLA—A＊0201-BSP融合基因并测序证实，构建的pBV220-HLA—A＊0201-BSP可在大肠杆菌DH50t中高效表达HLA—A＊0201-BSP融合蛋白．表达量占菌体总蛋白的28％，以包涵体的形式表达，经洗涤、变性后，以Sepharcyl S-300HR（S-300）柱层析纯化，纯度可达90％以上。结论：获得了高效表达HLA—A＊0201-BSP的大肠杆菌工程菌株，建立了简便有效的包涵体纯化方法，为制备HLA-A＊0201-肽四聚体奠定了基础。     

可溶性HLA-A*0201-PR1复合物的构建与鉴定

为制备HLA-A＊0201-PR1四聚体,本课题构建了可溶性的HLA-A＊0201-PR1复合物。以原核表达的HLA-A＊0201-BSP融合蛋白为重链,β2-微球蛋白（β2m）为轻链,与人工合成的HLA-A2限制性抗原肽PR1（蛋白酶3的第169-177氨基酸,VLQELNVTV）进行共折叠复性,以生成可溶性HLA-A＊0201-PR1复合物。应用BirA酶对复性混和物进行生物素化,再经阴离子交换柱纯化,得到生物素化的可溶性HLA-A＊0201-PR1复合物。应用凝胶过滤高效液相色谱分析可溶性HLA-A＊0201-PR1复合物的生成率。利用HLA-A2构象特异性抗体（BB7.2）及链霉亲和素进行Western blot和ELISA分析,对生物素化的可溶性HLA-A＊0201-PR1复合物进行鉴定。结果表明：在折叠体系中,主要含有HLA-A＊0201-BSP聚合体、HLA-A＊0201-PR1复合物及β2m,其中可溶性复合物生成率约18%。获得的HLA-A＊0201-PR1复合物可在BirA酶作用下被有效生物素化。结论：成功地获得了生物素化的可溶性HLA-A＊0201-PR1复合物,为进一步制备HLA-A＊0201-PR1四聚体创立了基础。     

Immunization of HLA-A*0201 and/or HLA-DPbeta1*04 patients with metastatic melanoma using epitopes from the NY-ESO-1 antigen

HLA class I-restricted peptides are often used in peptide vaccine regimens. There is strong evidence that many of these peptides can generate specific CD8 T-cell responses in vivo; however, only occasional objective clinical responses have been reported. To test whether provision of "help" would enhance antitumor immunity, the authors initiated a clinical trial in which patients with metastatic melanoma were immunized against the NY-ESO-1 tumor antigen, using an HLA-A2-restricted peptide (ESO-1:165V), an HLA-DP4-restricted peptide (NY-ESO-1:161-180), or both peptides given concomitantly. The first cohorts received only ESO-1:165V, using three vaccination schedules. Immunologically, most patients developed immune responses to the HLA-A2-restricted native ESO-1 epitope after vaccination. Peptide vaccine given daily for 4 days appeared to induce immunologic responses more rapidly than if given once a week or once every 3 weeks. In contrast, vaccination using the NY-ESO-1:161-180 peptide induced immune responses in only a few patients. Clinically, one patient who received NY-ESO-1:161-180 peptide alone had a partial response lasing 12 months. Concomitant vaccination with the HLA class II-restricted peptide did not alter the immune response to the HLA class I-restricted peptide form NY-ESO-1. However, vaccination with the HLA-A2-restricted epitope generated primarily T cells that did not recognize tumor after in vitro sensitization. This result raises questions about the use of synthetic peptides derived from NY-ESO-1 as a sole form of immunization.     

结核杆菌抗原Rv0173的HLA-A*0201限制性CTL表位的预测及鉴定

目的 鉴定结核杆菌(Mycobacterium tuberculosis,Mtb)抗原Rv0173中的HLA-A*0201限制性CTL表位.方法 应用数据库SYFPETTHI预测结核杆菌Rv0173中可能存在的HLA-A*0201限制性CTL表位,经流式细胞术分析各抗原肽与HLA-A*0201的亲合力,经时间分辨荧光法检测外周血单个核细胞(PBMCs)对各抗原肽产生的增殖反应,经细胞毒性实验研究各抗原肽诱导的特异性T细胞的细胞毒杀伤活性,逐步鉴定Rv0173的HLA-A*0201限制性CTL表位.结果 位于Rv0173氨基酸序列肽3(21-30aa)和抗原肽7(161-170aa)与HLA-A*0201分子具有较高的亲合力,并都能刺激HLA-A*0201阳性个体PBMCs增殖,并诱导产生特异性杀伤活性.结论 肽3(RLSQSADQYL)(21-30aa)和肽7(LLRGGGLVNL)(161-170aa)是抗原Rv0173上HLA-A*0201限制性CTL的优势表位,可作为结核疫苗设计的候选表位.     

Correct heteroduplex formation for mutation detection analysis.

BACKGROUND: The majority of mutation detection methods for unknown mutations are polymerase chain reaction (PCR)-based methods dependent on the formation of heteroduplexes between wild-type and mutant strands of DNA. METHODS AND RESULTS: This report discusses the difficulties associated with forming heteroduplexes with a large DNA fragment and the implications for subsequent mutation detection by the chemical cleavage of mismatch technique and other methods reliant on heteroduplex formation. It was found that the size and sequence context of the fragment being investigated inhibited correct heteroduplex formation. The problem was overcome by dividing the sequence into two overlapping fragments. CONCLUSIONS: Early identification of this problem in other fragments will help with the rapid optimization of PCR-based mutation detection methods.     

KLIANNTRV是结核抗原Ag85A的HLA-A*0201限制性CTL表位

目的鉴定结核杆菌抗原Ag85A的HLA-A*0201限制性CTL优势表位。方法采用数据库SYFPEITHI初步预测结核抗原Ag85A的HLA-A*0201限制性CTL表位;经流式细胞术分析抗原肽与HLA-A*0201的亲和力;经时间荧光分辨法检测患者外周血单个核细胞(PBMCs)对抗原肽的增殖反应;最后通过细胞毒实验逐步鉴定Ag85A的HLA-A*0201限制性CTL预测的表位。结果实验证明,预测的位于Ag85A氨基酸序列(242-250aa)的肽表位与HLA-A*0201具有较高的亲和力。结论筛选出的KLIANNTRV(242-250aa)是结核杆菌抗原Ag85A的HLA-A*0201限制性CTL优势表位。     

HLA-A*110104新等位基因的克隆与序列分析

目的识别并确认中国人群HLA新等位基因。方法采用基因克隆、测序及生物信息学技术,分析HLA新等位基因与HLA已知基因序列的差异。建立HLA新等位基因序列特异引物聚合酶链反应(PCR-SSP)分型方法,并对1200名HLA-A*11阳性的造血干细胞移植无关供者(包含100名HLA-A*11纯合子个体)进行HLA新等位基因筛选和频率分析。结果HLA新基因与A*110101的差异只是在外显子3区域中279位碱基发生C→T突变,导致93位密码子由CAC变为CAT,但氨基酸未发生变化,并最终被世界卫生组织HLA因子命名委员会正式命名为HLA-A*110104。该新基因出现在2个无关家系中,分别具有2～3代遗传史。在1200名无关供者中未发现其他带有新基因的个体。其基因频率为0．000 83。结论HLA-A*110104新基因具有稳定的遗传性和一定的普遍性,对无关供者的选择和人类学、遗传学等的研究具有一定意义。     

PCR-SSO流式荧光微珠法HLA-A*02高分辨分型检测模棱两可结果的统计分析

背景:由于HLA的复杂多态性,实际分型过程中难免会出现一些结果判读模棱两可现象.目的:统计分析基于PCR-SSO 流式荧光微珠HLA-A*02高分辨分型方法的模棱两可组合结果种类、比例,探讨解决模棱两可解决方法,提高高分辨分型比例.方法:对河南骨髓库捐献者 1 100人份HLA分型结果进行统计分析,计数法进行分类统计分析软件给出的包含HLA-A*02:01\02:09模棱两可组合代码,计算百分比;与确认为A*02:09的基因多态性分布进行比对,找出与A*02:09关联性较强的等位基因,用补充实验进行复核、确认,建立A*02:01\02:09模棱两可组合的判读方法.结果与结论:1 039例有效数据中包含A*02:01\02:09模棱两可组合279例(279/1 039,26.853%),代码种类19种,检出比例较高的有DMDC,DYVK,GMDD,GMDE;34例确认为A*0209的基因多态性统计显示A*0209的出现与A*11:01 (0.147 1)B*07:02(0.264 7)、DRB1*01:01(0.264 7 )、DRB1*03:01(0.117 6)有较强关联,选出高风险标本38例,经检测外显子1~7,并用SBT复核确认有1例结果为A*02:09(代码组合为GMDC),其余241例未检出A*02:09.提示 A*02:09的出现与B*07:02、DRB1*01:01、DRB1*03:01有较强关联,重点对这些关联标本进行外显子1~7检测,可有效地检出A*02:09.通过统计分析制定合理的判定规则和必要的复核实验可有效地简化操作程序,节省时间,降低费用,提高高分辨比例.     

Lack of strong immune selection pressure by the immunodominant, HLA-A*0201-restricted cytotoxic T lymphocyte response in chronic human immunodeficiency virus-1 infection.

Despite detailed analysis of the HIV-1-specific cytotoxic T lymphocyte response by various groups, its relation to viral load and viral sequence variation remains controversial. We analyzed HLA-A*0201 restricted cytotoxic T lymphocyte responses in 17 HIV-1-infected individuals with viral loads ranging from < 400 to 221,000 HIV RNA molecules per milliliter of plasma. In 13 out of 17 infected subjects, CTL responses against the SLYNTVATL epitope (p17 Gag; aa 77-85) were detectable, whereas two other HLA-A*0201 restricted epitopes (ILKEPVHGV, IV9; and VIYQYMDDL, VL9) were only recognized by six and five individuals out of 17 individuals tested, respectively. Naturally occurring variants of the SL9 epitope were tested for binding to HLA-A*0201 and for recognition by specific T cell clones generated from five individuals. Although these variants were widely recognized, they differed by up to 10,000-fold in terms of variant peptide concentrations required for lysis of target cells. A comparison of viral sequences derived from 10 HLA-A*0201-positive individuals to sequences obtained from 11 HLA-A*0201-negative individuals demonstrated only weak evidence for immune selective pressure and thus question the in vivo efficacy of immunodominant CTL responses present during chronic HIV-1 infection.     

Phase I clinical study with multiple peptide vaccines in combination with tetanus toxoid and GM-CSF in advanced-stage HLA-A*0201-positive melanoma patients

Successful induction of functional tumor-specific T cells by peptide vaccination in animal models has resulted in many clinical trials to test this approach in advanced-stage melanoma patients. In this phase I clinical trial, 11 end-stage melanoma patients were vaccinated intradermally with 3 peptides: MART-1(26-35) E27L (ELAGIGILTV), tyrosinase(368-376) N375Q (YMDGTMSQV), and gp100(209-217) T210M (IMQVPFSV), admixed with tetanus toxoid and granulocyte-monocyte colony stimulating factor. The peptide vaccine was well tolerated at all tested doses, and led to grade 1-2 toxicity only. Although all patients did show a rise in antitetanus IgG titers, in only 3 patients peptide-specific CD8 T-cells were induced. In 2 cases, the response was directed against MART-1(26-35) and consisted of 0.2% and 3.3% of the CD8 population; however, in both instances these cells did not produce interferon-gamma on stimulation with the unmodified peptide. The third patient mounted a small (0.1%) response against gp100. In a fourth patient, a nonfunctional tyrosinase-specific response (0.6%) was found that was present before vaccination, but was not affected in size nor in function by the vaccine. None of the 11 patients responded clinically according to response evaluation criteria in solid tumors criteria. Although this study is a small scale phase I clinical trial, the efficacy that was observed was disappointingly low. In accordance with previously published peptide vaccination studies, these results add to the increasing evidence that peptide vaccination in itself is not potent enough as an effective melanoma immunotherapy in advanced-stage patients.     

Capillary electrophoresis-based heteroduplex analysis with a universal heteroduplex generator for detection of point mutations associated with rifampin resistance in tuberculosis.

BACKGROUND: Slab gel heteroduplex analysis (HDA), a popular scanning method for genetic mutations, uses DNA fragments typically generated by PCR to create homo- and heteroduplex molecules with conformational differences and sequence-dependent electrophoretic profiles. Use of a universal heteroduplex generator (UHG) enhances the subtle variations caused by single-base substitutions. METHODS: The HDA-UHG slab gel format was modified for an efficient capillary-based method. The effect of staining dyes TOPRO5 and YOPRO1 on the analysis of heteroduplexes was studied, as well as ultraviolet absorbance and laser-induced fluorescence (LIF) detection methods. In addition, the entangled polymers hydroxyethyl cellulose, methyl cellulose, and linear polyacrylamide were evaluated as separation matrices. RESULTS: This assay was able to detect the presence of Mycobacterium tuberculosis and its rifampin susceptibility directly from clinical specimens in dramatically reduced analysis time (30 min vs 2.5 h). Optimized conditions included 0.3% methyl cellulose as the separation matrix, on-line staining using 1 micromol/L YOPRO1, and LIF detection for quantitative and reproducible analysis of single-base substitutions in the rifampin resistance-determining region of rpoB that give rise to the rifampin-resistant phenotype of M. tuberculosis. We generated 95% confidence limits using the wild-type sequence and used these limits to determine rifampin susceptibility in samples. CONCLUSIONS: Capillary electrophoresis, combined with the HDA-UHG technique, may be of value for rapid and efficient clinical diagnosis of rifampin-resistant tuberculosis strains.     

High-resolution gas chromatographic analysis of phenolic acids and alcohols using capillary columns

The application of the two types of capillary column, wall-coated open tubular and support-coated open tubular to the analysis of volatile derivatives of phenolic acids and alcohols is critically assessed. The latter columns were more versatile and suitable for urinary analysis. Because capillary columns possess high resolving ability, it has been possible to separate such geometrical isomers as 4-hydroxy-3-methoxyphenylacetic acid and 3-hydroxy-4-methoxyphenylacetic acid from biological samples. The most satisfactory results were obtained using a serial connection of a 50 ft OV-I7 and a 50-ft SE-30 column.     

Quantitation of CD8+ T cell responses to newly identified HLA-A*0201-restricted T cell epitopes conserved among vaccinia and variola (smallpox) viruses

Immunization with vaccinia virus resulted in long-lasting protection against smallpox and was the approach used to eliminate natural smallpox infections worldwide. Due to the concern about the potential use of smallpox virus as a bioweapon, smallpox vaccination is currently being reintroduced. Severe complications from vaccination were associated with congenital or acquired T cell deficiencies, but not with congenital agammaglobulinemia, suggesting the importance of T cell immunity in recovery from infection. In this report, we identified two CD8+ T cell epitopes restricted by the most common human major histocompatibility complex (MHC) class I allele, HLA-A*0201. Both epitopes are highly conserved in vaccinia and variola viruses. The frequency of vaccinia-specific CD8+ T cell responses to these epitopes measured by interferon (IFN)-gamma enzyme-linked immunospot (ELISPOT) assay and HLA/peptide tetramer staining peaked 2 wk after primary immunization and then declined, but were still detectable 1 to 3 yr after primary immunization. 2 wk after immunization, IFN-gamma-producing cells specific to these two epitopes were 14% of total vaccinia virus-specific IFN-gamma-producing cells in one donor, 35% in the second donor, and 6% in the third donor. This information will be useful for studies of human T cell memory and for the design and analyses of the immunogenicity of experimental vaccinia vaccines.     

Efficient identification of novel HLA-A(*)0201-presented cytotoxic T lymphocyte epitopes in the widely expressed tumor antigen PRAME by proteasome-mediated digestion analysis

We report the efficient identification of four human histocompatibility leukocyte antigen (HLA)-A(*)0201-presented cytotoxic T lymphocyte (CTL) epitopes in the tumor-associated antigen PRAME using an improved "reverse immunology" strategy. Next to motif-based HLA-A(*)0201 binding prediction and actual binding and stability assays, analysis of in vitro proteasome-mediated digestions of polypeptides encompassing candidate epitopes was incorporated in the epitope prediction procedure. Proteasome cleavage pattern analysis, in particular determination of correct COOH-terminal cleavage of the putative epitope, allows a far more accurate and selective prediction of CTL epitopes. Only 4 of 19 high affinity HLA-A(*)0201 binding peptides (21%) were found to be efficiently generated by the proteasome in vitro. This approach avoids laborious CTL response inductions against high affinity binding peptides that are not processed and limits the number of peptides to be assayed for binding. CTL clones induced against the four identified epitopes (VLDGLDVLL, PRA(100-108); SLYSFPEPEA, PRA(142-151); ALYVDSLFFL, PRA(300-309); and SLLQHLIGL, PRA(425-433)) lysed melanoma, renal cell carcinoma, lung carcinoma, and mammary carcinoma cell lines expressing PRAME and HLA-A(*)0201. This indicates that these epitopes are expressed on cancer cells of diverse histologic origin, making them attractive targets for immunotherapy of cancer.     

High-resolution melting analysis using unlabeled probe and amplicon scanning simultaneously detects several lactase persistence variants

Lactase persistence and thereby tolerance to lactose is a common trait in people of Northern European descent. It is linked to the LCT -13910C>T variant located in intron 13 of the MCM6 gene 13.9 kb upstream of the lactase (LCT) gene. In people of African and Middle Eastern descent, lactase persistence can be associated with other variants nearby the -13910C>T variant, limiting the use of the -13910C>T-based SNP analysis, e.g. TaqMan assays for the diagnosis of lactose intolerance. Using high-resolution melting analysis, we identified five samples that were heterozygous for the -13915T>G variant among 78 patients genotyped as -13910C/C by a TaqMan assay. All samples originated from patients of probable Middle Eastern descent. In order to detect the -13910 and -13915 variants simultaneously, we developed a new high-resolution melting (HRM) analysis assay based on unlabeled probe genotyping and simultaneous amplicon scanning analysis. By using this assay we were able to distinguish the -13910 and -13915 genotypes clearly. Furthermore, we identified two rare variants, the -13907C>G and -13913T>C. With this method, based on an inexpensive unlabeled probe, it is possible to simultaneously detect the -13910C>T and -13915T>G variants in addition to rarer variants surrounding the -13910 site. This new method may contribute to improve the diagnostic performance of the genetic analysis for lactose intolerance.     

High-resolution melting analysis using unlabeled probe and amplicon scanning simultaneously detects several lactase persistence variants

Abstract

Lactase persistence and thereby tolerance to lactose is a common trait in people of Northern European descent. It is linked to the LCT ?13910C>T variant located in intron 13 of the MCM6 gene 13.9 kb upstream of the lactase (LCT) gene. In people of African and Middle Eastern descent, lactase persistence can be associated with other variants nearby the ?13910C>T variant, limiting the use of the ?13910C>T-based SNP analysis, e.g. TaqMan assays for the diagnosis of lactose intolerance. Using high-resolution melting analysis, we identified five samples that were heterozygous for the ?13915T>G variant among 78 patients genotyped as ?13910C/C by a TaqMan assay. All samples originated from patients of probable Middle Eastern descent. In order to detect the ?13910 and ?13915 variants simultaneously, we developed a new high-resolution melting (HRM) analysis assay based on unlabeled probe genotyping and simultaneous amplicon scanning analysis. By using this assay we were able to distinguish the ?13910 and ?13915 genotypes clearly. Furthermore, we identified two rare variants, the ?13907C>G and ?13913T>C. With this method, based on an inexpensive unlabeled probe, it is possible to simultaneously detect the ?13910C>T and ?13915T>G variants in addition to rarer variants surrounding the ?13910 site. This new method may contribute to improve the diagnostic performance of the genetic analysis for lactose intolerance.     

High-resolution melting curve analysis for genotyping of common SNP in MTHFR gene using fixed-cell suspension

Genetic variation in MTHFR might explain the interindividual differences in both therapeutic and toxic responses to the treatment of cancer and rheumatoid arthritis with methotrexate, and can be involved in the sensitivity of developing diseases like cancer and congenital anomalies. We investigated the common sequence variation, C677T, in the MTHFR gene in fixed-cell specimens archived after chromosomal analysis using a novel gene scanning method based on post PCR analysis of high-resolution melting curves (HRM). These fixed specimens were stored after routine chromosomal analysis for 1 year at -20 degrees C in a 3:1 methanol:acetic acid solution. The method revealed a distinct pattern between homozygous and heterozygous alleles. Sensitivity and specificity of the HRM based method were comparable to that obtained by a hybridization probe. While the success rate for genotyping of a common SNP in MTHFR was similar to the hybridization probe approach, the HRM based method was more cost-effective and had a shorter turnaround time.     

Muscle protein analysis. I. High-resolution two-dimensional electrophoresis of skeletal muscle proteins for analysis of small biopsy samples.

We have been developing a clinically useful method for high-resolution two-dimensional electrophoretic analysis of small (5--10 mg) human muscle biopsy samples with sufficient resolution to resolve the major contractile proteins and enzymes. Using rabbit psoas muscle as a model, we describe methods for sample preparation and two-dimensional electrophoresis. Basic proteins, which appear as streaks when conventional isoelectric focusing is used in the first dimension, are resolved through a modification of the nonequilibrium pH gradient electrophoresis method [Cell 12, 1133 (1977)]. In the two-dimensional patterns obtained from rabbit muscle, we identify the components of 10 enzymes and of myosin, actin, tropomyosin, and troponin. These patterns indicate charge heterogeneity in a large fraction of the proteins. Comparison of rabbit and normal human muscle patterns shows many similarities, but much additional work is required to confirm identifications. We conclude that analysis of small biopsy samples is feasible, but that all aspects of human sample acquisition, storage (when necessary), and preparation require thorough study before the method becomes routine in human muscle research and, ultimately, in the diagnosis of some muscle diseases.     

Time-variant partial directed coherence in analysis of the cardiovascular system. A methodological study

Time-variant partial directed coherence (tvPDC) is used for the first time in a multivariate analysis of heart rate variability (HRV), respiratory movements (RMs) and (systolic) arterial blood pressure. It is shown that respiration-related HRV components which also occur at other frequencies besides the RM frequency (= respiratory sinus arrhythmia, RSA) can be identified. These additional components are known to be an effect of the 'half-the-mean-heart-rate-dilemma' ('cardiac aliasing' CA). These CA components may contaminate the entire frequency range of HRV and can lead to misinterpretation of the RSA analysis. TvPDC analysis of simulated and clinical data (full-term neonates and sedated patients) reveals these contamination effects and, in addition, the respiration-related CA components can be separated from the RSA component and the Traube-Hering-Mayer wave. It can be concluded that tvPDC can be beneficially applied to avoid misinterpretations in HRV analyses as well as to quantify partial correlative interaction properties between RM and RSA.