结核分枝杆菌重组MPT64蛋白抗原诱发豚鼠迟发型超敏反应的研究

结核菌素纯蛋白衍生物 (ＰＰＤ)含多种蛋白成分 ,与多种分枝杆菌存在交叉 ,尤其在鉴别结核菌感染和卡介苗接种阳转者上有一定的困难 ,所以ＰＰＤ作为结核病诊断试剂有其局限性。现已发现结核分枝杆菌Ａｇ85、ＭＰＴ64、38ｋＤ抗原、ＭＰＴ63、ＥＳＡＴ6等 ,均能诱发豚鼠发生迟发性超敏反应[1] 。具有高特异性的新的诊断试剂或许就存在于他们或他们的组合中。ＭＰＴ64蛋白是结核分枝杆菌生长过程中的分泌蛋白 ,它能诱发结核分枝杆菌感染的豚鼠发生很强的ＤＴＨ反应 ,部分ＢＣＧ在减毒过程中丢失了编码该蛋白的基因 ,特异性较强 ,用于皮肤试验…     

结核分枝杆菌MPT64重组母牛分枝杆菌免疫学特性

目的:研究结核分枝杆菌MPT64重组母牛分枝杆菌疫苗免疫学特性.方法:用分泌表达MPT64的重组母牛分枝杆菌疫苗免疫BALB/c小鼠,ELISA法检测免疫小鼠的特异性抗体滴度和抗体亚类.分离免疫小鼠脾淋巴细胞,检测淋巴细胞增殖、IFN-γ和IL-12产生水平、CD4+细胞和CD8+细胞数、脾淋巴细胞特异性CTL杀伤效应.毒株攻击后对脾脏细菌负荷计数.结果:MPT64重组母牛分枝杆菌疫苗免疫可诱导小鼠高水平的体液免疫应答,免疫小鼠脾淋巴增殖明显,IFN-γ和IL-12含量增加,CD4+和CD8+细胞百分比明显增加,CTL杀伤效应明显,对MTB H37Rv攻击后有一定的保护作用.结论:MPT64重组母牛分枝杆菌疫苗可诱导小鼠有效的体液和细胞免疫应答,有可能作为新型TB疫苗候选.     

MPT64--卡介苗重组疫苗的构建

全球有三分之一的人口约2 0亿感染过结核分枝杆菌,其中16 0 0万人处于活跃期,每年有约10 0 0万新感染者。由于用药的不规范,耐药和耐多药结核病显著增多,增加了治疗的难度;流动人口的增加使结核病的传播机会增加;而艾滋病与结核病合并感染,使问题变的更为严峻。当前预防结核病的卡介苗效果在不同地区有很大差异,改进疫苗的要求提到日程。MPT6 4是结核分枝杆菌分泌蛋白中含量较多的一种,具有免疫保护力,是亚单位疫苗和核酸疫苗的候选者之一。本研究通过穿梭质粒将基因导入卡介苗,希望能在卡介苗中表达MPT6 4蛋白,增强其免疫原性和保护力。…     

结核分枝杆菌Ag85B-MPT64融合基因疫苗的免疫效果观察

目的:研究并比较结核分枝杆菌(H37Rv)Ag85B、MPT64DNA.以及两者的融合基因(AM)的免疫原性。方法:雌性C57BL/6小鼠25只,随机分为5组,即A组(PBS)、B组(peDNA3.1)、C组(pcDNA/Ag85B)、D组(pcDNA/MPT64)和E组(pcDNA/AM)。分别于胫前肌注射7.5 g/L利多卡因和质粒混合物(1:4,100μL,含质粒70μg/次),间隔2 wk免疫 1次,共3次。末次免疫后4 wk取血分离血清测定总IgG,同时分离脾淋巴细胞,用PPD刺激后分别做脾淋巴细胞增殖实验(MTT比色法)和测定脾淋巴细胞培养上清中IFN-γ的水平。结果:Ag85B、MPT64和AM质粒DNA,均能诱导小鼠产生较高水平的PPD特异性IgG。免疫小鼠脾淋巴细胞体外经PPD刺激后,能产生特异性淋巴细胞增殖和分泌IFN-γ。peDNA/AM组IFN-γ的分泌水平明显高于pcDNA/Ag85B和pcDNA/MPT64免疫组(P<0.05)。结论:结核分枝杆菌Ag85B-MPT64融合基因疫苗,能在小鼠体内诱导特异性细胞和体液免疫。     

结核分枝杆菌DNA指纹技术研究及其应用

目的：建立限制性内切酶片段长度多态性(RFLP)方法分析结核分枝杆菌DNA指纹并探讨其分子流行病学特点及与药物敏感性的关系。方法：提取结核分枝杆菌DNA,经内切酶PvuⅡ酶切、琼脂糖凝胶电泳、Southem转印后,与地高辛标记的IS6110探针杂交,以酶免疫试验检测信号,比较各临床分离株IS6110指纹。结果：根据IS6110指纹特征的同源性的高低,将所检测的127株结核分枝杆菌分为A、B、C和D4簇,4簇的株数(比例)分别为50(39．4％)、12(9．4％)、16(12．6％)和49(38．6％)。各簇菌株的IS6110指纹特征：A簇菌株间相似系数在70％以上,共同拥有1．3kb、1．9kb、2．1kb、2．7kb、3．3kb、4．5kb、5．0kb、6．5kb等位置的条带;B簇菌株间相似系数也在70％以上,与A簇菌株族间相似系数较高,为65％,与A簇相比,1．9kb以上条带与A簇相似,但缺乏1．9kb以下的条带;C簇带型分布散且较为平均,在1．3kb、2．2kb、3．3kb、5．5kb等位置都有共同拥有的片段;D簇菌株条带数目少,呈现高度多态性,所有菌株之间没有相同位置的条带,相互间同源性较低。其中A、B、C 3簇相似系数在55％以上,且有相同位置的片段,将它们称为“成簇菌株”。无共同条带的D簇称为“不成簇菌株”。30岁以上人群“不成簇菌株“所占比重高于30岁以下人群,低年龄组“成簇菌株”比例高,近期传播结核较为严重。检测菌株的多态性变化在结核分枝杆菌耐药与敏感株中的分布,A族菌株的耐药比例低于其它3簇菌株。未发现结核分枝杆菌DNA指纹特征与居住状况和职业之间的联系,也没有发现传播频率在男女性别之间存在差异。结论：深圳地区菌株基因型与北京地区菌株相似。深圳地区低年龄组(30岁以下)的结核病传播以近期传播为主。与北京地区相似菌株耐药比例低于其它型菌株。     

结核分枝杆菌Ag85A质粒DNA疫苗治疗小鼠耐药结核病的效果研究

目的 研究结核分枝杆菌Ag85A质粒DNA疫苗治疗小鼠耐药结核病的效果.方法 用结核分枝杆菌高耐利福平低耐异烟肼临床分离株HB361尾静脉注射17～19 g的6～8周龄雌性BALB/c小鼠后,将小鼠随机均匀地分为6组,感染后第3天开始,分别用生理盐水(A组)、pVAX1空载体(B组)、利福平(C组)、微卡菌苗(D组)、Ag85A质粒DNA疫苗(E组)、利福平和Ag85A质粒DNA疫苗(F组)治疗60d,每组10只小鼠.治疗结束后3周,分别取肺和脾观察病理改变,称取重量做菌落计数.结果 治疗结束后3周,与对照组比较,D组、E组和F组肺脏病变有不同程度减轻,病变局限,病变范围分别为50%、20%、20%,2/3区域可见正常的肺泡结构,肺泡轮廓相对清晰,细胞分布均匀.与A组相比,D组、E组和F组肺脏菌落数分别减少了52%、68%、78%;脾脏菌落数依次减少了48%、65%、79%.结论 与对照组相比,Ag85A质粒DNA疫苗单独应用或与利福平联合应用治疗小鼠耐药结核病均显示疗效.     

SELEX:一种体外筛选核酸适配子的新技术

SEL EX技术是一项新的体外筛选技术 ,它是用体外合成的、其库容为 1 0 1 5左右的随机寡核苷酸库与靶物质结合 ,通过数轮的筛选与扩增 ,筛选到靶物质的目的 DNA或 RNA片段 ,对疾病的诊断与治疗方面起着重要的作用 ,为核酸的结构和功能的研究 ,提供了一个有效的方法     

筛选HIV-1 P24蛋白适配子的一种简便的SELEX方法

目的 快速筛选HIV-1 P24抗原适配子,并验证其特异性与亲和力.方法 利用聚碳酯材料PCR板包被P24抗原,在PCR板中运用SELEX技术进行适配子筛选.对多条适配子序列进行了一级结构及二级结构软件分析.酶联免疫法(ELISA)对筛选到的适配子进行亲和力及特异性验证.结果 确定用聚碳酯材料可以包被P24抗原,ELISA法检测抗原包被浓度与吸光度(A值)正相关;电泳显示适配子得到富集筛选;测序后软件分析表明多条适配子有共有序列,空间结构多样;用ELISA法,结合辣根过氧化物酶(HRP)标记链霉亲和素(SA)与生物素标记的适配子,对适配子与P24的亲和力进行验证,表明筛选到的适配子与P24抗原有特异性的高亲和力结合.结论 建立了一种简便的筛选HIV-1 P24抗原适配子的方法,筛选到特异性的高亲和力P24适配子.     

聚合酶链反应检测结核分枝杆菌DNA诊断关节结核的临床评价

目的评价聚合酶链反应(polymerase chain reaction,PCR)检测关节结核标本结核分枝杆菌脱氧核糖核酸(deoxyribonucleic acid,DNA)诊断关节结核的临床价值。方法对20份标准标本(5份结核分枝杆菌标准菌株、5份卡介苗和10份其它细菌标本)分别应用PCR盲法检测结核分枝杆菌DNA。对95例关节结核标本和98例非关节结核标本分别应用PCR检测结核分枝杆菌DNA。应用疾病诊断方法的临床评价原则对PCR诊断关节结核的敏感性、特异性和准确性进行评价。结果 (1)20份标准标本PCR检测中,结核分枝杆菌和卡介苗均为阳性,而其它细菌均为阴性;(2)95例关节结核标本中,PCR阳性78例、阴性17例;98例非关节结核标本中,PCR阳性9例、阴性89例;(3)PCR检测关节结核标本结核分枝杆菌DNA的敏感性为82.11%、特异性为90.81%、准确性为86.60%、阳性预测值为89.80%、阴性预测值为84.00%;(4)PCR整个检测过程自动化控制,可在3~6h内完成。结论 PCR是一种敏感、特异、快速、简便、无创、标本微量的关节结核标本结核分枝杆菌检测方法,对于关节结核的早期、快速诊断与鉴别诊断具有极其重要的临床价值。     

结核分枝杆菌Rv2450蛋白诱导小鼠免疫应答的实验研究

目的:以原核表达的结核分枝杆菌Rv2450蛋白在小鼠体内诱导体液和细胞免疫应答。方法:采用皮下包埋的方法,以预先转移到硝酸纤维素膜上的原核表达的Rv2450蛋白免疫小鼠(10只)3次,每次间隔2周。用间接ELISA法检测免疫小鼠血清特异性抗体的滴度。末次免疫完成后4周,处死3只免疫小鼠并分离脾淋巴细胞,体外经PPD(2μg/孔)刺激后,用MTT比色法检测免疫小鼠脾淋巴细胞的增殖指数。用ELISA法检测脾淋巴细胞悬液中IFN-γ、IL-10及IL-12的水平。结果:Rv2450蛋白免疫小鼠血清特异性抗体的滴度为1∶3200,淋巴细胞增殖指数为3.76±0.19。免疫小鼠脾淋巴细胞培养液中IFN-γ、IL-10及IL-12的含量,分别为(1740±19)ng/L、(678±15)ng/L、(469±13)ng/L,均高于各组的生理盐水对照组(P<0.05)。结论:Rv2450有可能作为新型结核疫苗的候选组分。     

MPT64抗体的适体在结核病血清学检测中的应用

目的 利用SELEX技术筛选MPT64抗体的适体建立混合夹心ELISA检测体系,应用于临床血清标本的检测,探讨该方法 潜在的实验室诊断价值.方法 利用竞争ELISA检测方法 ,测定不同浓度的MPT64抗原对最后一轮ssDNA文库与靶物质亲和力的抑制率,选取优势序列且亲和性值较高的适体用于检测,优化混合夹心ELISA检测方法 ,确定MPT64抗体的检测下限和线性范围,同时检测230例临床血清标本.结果 在竞争ELISA结果 中,总反应体系为100μl,MPT64抗原浓度由2μg/ml增加到256 μg/ml时,对ssDNA文库的抑制率也由0.25%增加到80%.优化的混合夹心ELISA的检测体系:ssDNA包被浓度为0.1μg/孔、血清稀释度为1/200、辣根过氧化物酶标记的羊抗人IgG抗体浓度为1/40 000.MPT64抗体的检测下限为3 mg/L,线性范围为10～1000 mg/L.利用该体系检测100例结核病患者、100例健康体检者和30例非结核病患者血清,检测结果 用GraphpadPrism软件进行分析,结核病组与健康体检组、结核病组与非结核疾病对照组差异均具有统计学意义(P<0.001).统计学分析得到检测的特异性与敏感性分别为96.1%和31.0%.结论 利用适体建立的混合夹心ELISA用于结核病的血清学诊断具有一定的诊断价值.     

Characterization of a Mycobacterium leprae antigen related to the secreted Mycobacterium tuberculosis protein MPT32.

Secreted proteins may serve as major targets in the immune response to mycobacteria. To identify potentially secreted Mycobacterium leprae antigens, antisera specific for culture filtrate proteins of Mycobacterium tuberculosis were used to screen a panel of recombinant antigens selected previously by leprosy patient sera. Four potentially secreted antigens were identified by this approach, and one was recognized by antibodies specific for MPT32, a secreted M. tuberculosis protein. The DNA coding for the M. leprae antigen, which we have designated 43L, was isolated and characterized and found to encode a 25.5-kDa protein that is preceded by a consensus signal peptide of 39 amino acids. The N-terminal amino acid sequence of 43L shows 50% homology with the 20 known N-terminal amino acids of MPT32, and 47% homology was found with the N terminus of a 45/47-kDa antigen complex identified in Mycobacterium bovis BCG. These findings indicate that 43L represents an antigen related to MPT32 and the M. bovis BCG 45/47-kDa complex and that 43L is likely to be a protein secreted by M. leprae. Purified recombinant 43L protein is recognized by antibodies and T cells from healthy contacts and leprosy patients, illustrating that secreted proteins are of importance in the immune response to M. leprae.     

Molecular Characterization of MPT83: a Seroreactive Antigen of Mycobacterium tuberculosis with Homology to MPT70

The Mycobacterium bovis antigens MPB70 and MPB83 are homologous cross-reactive proteins. It has been reported previously that MPB83 is glycosylated and exists in two forms with apparent molecular masses of 23 kDa and 25 kDa, whereas the apparent molecular mass of MPB70 is 22 kDa. Using a monoclonal antibody, SB10, which recognizes an epitope common to both MPB70 and MPB83, we compared the expression of these proteins in M. bovis BCG, virulent M. bovis and virulent Mycobacterium tuberculosis by Western blotting of bacterial lysates. The previously described pattern of high and low producing substrains of BCG for MPB70 was also applicable for MPB83. Virulent M. bovis was found to express high levels of MPB70 and MPB83. Immunoblotting experiments using sera from Balb/c mice infected with live M. tuberculosis H37Rv revealed that although the MPB83 homologue of M. tuberculosis, MPT83, is expressed at low levels in M. tuberculosis when grown in vitro, the protein is highly immunogenic during infection with live bacteria. A clone from a mycobacterial shuttle cosmid library of M. tuberculosis H37Rv was isolated which expressed both MPT70 and MPT83. Genetic analysis of this cosmid revealed that MPT70 and MPT83 were encoded by separate genes with the gene encoding MPT83 situated 2.4 kb upstream of mpt70. Both genes are transcribed in the same direction. The gene encoding MPT83 was cloned and DNA sequencing revealed an open reading frame of 660 bp encoding a protein with a predicted molecular mass of 22 kDa. Recombinant MPT83 was expressed in Escherichia coli from the native AUG initiation codon by translational coupling. In E. coli MPT83 was expressed as a 23 kDa antigen whereas in the rapid growing mycobacterium Mycobacterium smegmatis the protein was expressed as a 25 kDa protein indicating post-translational modification of the protein by M. smegmatis. In recombinant M. smegmatis MPT83 was predominantly cell associated whereas MPT70 was secreted into the culture medium. Amino acid sequence comparison between MPT83 and MPT70 revealed a 61% identity between the proteins, although little homology was apparent at the amino terminus. In MPT83 this region contained a typical lipoprotein signal peptide cleavage motif and a putative signal motif for O glycosylation. Both these motifs were absent from the amino acid sequence of MPT70.     

Mapping of the delayed-type hypersensitivity-inducing epitope of secreted protein MPT64 from Mycobacterium tuberculosis.

The gene encoding the immunogenic protein MPT64 found in culture filtrates of Mycobacterium tuberculosis H37Rv was expressed in Escherichia coli K-12 and purified as a recombinant protein. The purified recombinant MPT64 elicited delayed-type hypersensitivity (DTH) in outbred guinea pigs sensitized with Mycobacterium bovis BCG Tokyo. The skin reactions were comparable to those obtained with native MPT64. No skin reactions were observed when either recombinant MPT64 or native MPT64 was used in guinea pigs sensitized with M. bovis BCG Danish 1331. Amino- and carboxy-terminal deletion mutants of MPT64 were purified as fusion proteins for the mapping of DTH-inducing epitopes on recombinant MPT64 by use of the guinea pig skin test model. The part of the molecule responsible for the biological activity was located at the carboxy-terminal end. Further studies with overlapping synthetic peptides have pinpointed the biological activity at a single DTH-inducing epitope consisting of 15 residues between amino acids Gly-173 and Ala-187. Screening by PCR of 56 clinical isolates of M. tuberculosis from Danish and Tanzanian patients demonstrated the presence of mpt64 in all of the strains. These results point to MPT64 as a possible candidate for a skin test reagent specific for diagnosis of human tuberculosis.     

Delayed-Type Hypersensitivity Responses to ESAT-6 and MPT64 from Mycobacterium tuberculosis in the Guinea Pig

Two antigens from Mycobacterium tuberculosis, ESAT-6 and MPT64, elicited delayed-type hypersensitivity (DTH) skin responses in outbred guinea pigs infected with M. tuberculosis by the aerosol and intravenous routes but not those sensitized with M. bovis BCG or M. avium. The DTH epitope of ESAT-6 was mapped to the C terminus. Nonresponders to the individual antigens were found, but all animals responded to a combination of ESAT-6 and MPT64 or their respective minimal target peptides. Correspondingly, these molecules could form the basis of a new skin test for tuberculosis.     

A DNA vaccine expressing CFP21 and MPT64 fusion protein enhances BCG-induced protective immunity against Mycobacterium tuberculosis infection in mice

The efficacy of Bacillus Calmette–Guérin (BCG) vaccine in preventing adult tuberculosis (TB) is highly variable. Genetic differences between BCG vaccine substrains, which can be divided into early strains and late strains based on the loss of region of difference two (RD2), may result in the variability and BCG substrains. The effect of lack of RD2 on the protective efficacy of BCG substrains against TB remains unknown. In this study, we demonstrated that CFP21 and MPT64(rCM) fusion protein, encoded by RD2 of Mycobacterium tuberculosis, could stimulate higher level of interferon (IFN)-γ in tuberculin skin test (TST)-positive healthy population than in TST-negative healthy population. Compared with naive mice challenged with virulent M. tuberculosis H37Rv, C57BL/6 mice vaccinated with pcD2164 DNA expressing rCM protein resulted in a greater decrease in the bacterial load of lung. Moreover, pcD2164 could boost the protective immunity in mice primed by BCG than BCG alone or DNA vaccination alone, as evidenced by lower bacterial load in the lung tissue and reduced lung pathology. The protection induced by BCG prime-DNA vaccine boost strategy was associated with significant increases in rCM protein-specific IFN-γ. Therefore, our results clearly indicate that the loss of RD2 has an important influence on the protective efficacy of different BCG substrains. These findings will benefit the optimal choice of BCG substrain for neonatal immunization and rational design of new vaccines for the prevention of TB.     

Identification of an HLA-A*0201-restricted T-cell epitope on the MPT51 protein, a major secreted protein derived from Mycobacterium tuberculosis, by MPT51 overlapping peptide screening

CD8+ T cells play a pivotal role in protection against Mycobacterium tuberculosis infection. We identified a novel HLA-A*0201-restricted CD8+ T-cell epitope on a dominant secreted antigen of M. tuberculosis, MPT51, in HLA-A*0201 transgenic HHD mice. HHD mice were immunized with plasmid DNA encoding MPT51 with gene gun bombardment, and gamma interferon (IFN-gamma) production by the immune splenocytes was analyzed. In response to overlapping synthetic peptides covering the mature MPT51 sequence, the splenocytes were stimulated to produce IFN-gamma by only one peptide, p51-70. Three-color flow cytometric analysis of intracellular IFN-gamma and cell surface CD4 and CD8 staining revealed that the MPT51 p51-70 peptide contains an immunodominant CD8+ T-cell epitope. Further analysis using computer algorithms permitted identification of a bona fide T-cell epitope, p53-62. A major histocompatibility complex class I stabilization assay using T2 cells confirmed that this epitope binds to HLA-A*0201. The T cells were capable of lysing MPT51 p53-62 peptide-pulsed T2 cells. In addition, MPT51 p53-62-specific memory CD8+ T cells were found in tuberculin skin test-positive HLA-A*0201+ healthy individuals. Use of this HLA-A*0201-restricted CD8+ T-cell epitope for analysis of the role of MPT51-specific T cells in M. tuberculosis infection and for design of vaccines against tuberculosis is feasible.     

Novel wide-range quantitative nested real-time PCR assay for Mycobacterium tuberculosis DNA: development and methodology

Previously, we designed an internally controlled quantitative nested real-time (QNRT) PCR assay for Mycobacterium tuberculosis DNA in order to rapidly diagnose tuberculous meningitis. This technique combined the high sensitivity of nested PCR with the accurate quantification of real-time PCR. In this study, we attempted to improve the original QNRT-PCR assay and newly developed the wide-range QNRT-PCR (WR-QNRT-PCR) assay, which is more accurate and has a wider detection range. For use as an internal-control "calibrator" to measure the copy number of M. tuberculosis DNA, an original new-mutation plasmid (NM-plasmid) was developed. It had artificial random nucleotides in five regions annealing specific primers and probes. The NM-plasmid demonstrated statistically uniform amplifications (F = 1.086, P = 0.774) against a range (1 to 10(5)) of copy numbers of mimic M. tuberculosis DNA and was regarded as appropriate for use as a new internal control in the WR-QNRT-PSR assay. In addition, by the optimization of assay conditions in WR-QNRT-PCR, two-step amplification of target DNA was completely consistent with the standard curve of this assay. Due to the development of the NM-plasmid as the new internal control, significantly improved quantitative accuracy and a wider detection range were realized with the WR-QNRT-PCR assay. In the next study, we will try to use this novel assay method with actual clinical samples and examine its clinical usefulness.     

Strain identification of Mycobacterium tuberculosis by DNA fingerprinting: recommendations for a standardized methodology.

DNA fingerprinting of Mycobacterium tuberculosis has been shown to be a powerful epidemiologic tool. We propose a standardized technique which exploits variability in both the number and genomic position of IS6110 to generate strain-specific patterns. General use of this technique will permit comparison of results between different laboratories. Such comparisons will facilitate investigations into the international transmission of tuberculosis and may identify specific strains with unique properties such as high infectivity, virulence, or drug resistance.