以丙氨酸消旋酶为靶点的高通量抗结核药物筛选模型的建立及应用

目的建立以结核分枝杆菌丙氨酸消旋酶为靶点的新型高通量抗结核药物筛选模型,筛选丙氨酸消旋酶的抑制剂,获得以丙氨酸消旋酶为靶点的新型抗结核药物先导物。方法以结核分枝杆菌H37Rv基因组为模板,pET28a表达质粒为载体,将alr基因克隆至pET28a,构建pET28a::alr重组表达质粒,表达并纯化得到重组结核分枝杆菌丙氨酸消旋酶;通过测定反应产物NADH在340 nm处光密度变化速率,检测酶反应活性,构建并优化该酶抑制剂的高通量筛选模型;应用该模型对化合物库进行筛选;测定活性化合物IC50以及对结核分枝杆菌的MIC。结果成功构建了结核分枝杆菌alr基因的表达载体;得到了纯度较高的重组丙氨酸消旋酶,测得该酶的比活力为13.53 kU/mg;所建立的丙氨酸消旋酶高通量筛选模型稳定性高,符合高通量筛选的要求;通过对70 000个化合物进行筛选,得到了5个活性较高的化合物,其中,IMB-XZ5对结核分枝杆菌的MIC为4~8μg/ml,且对结核分枝杆菌的作用具有较高的特异性。结论建立了稳定性好、灵敏度较高的结核分枝杆菌丙氨酸消旋酶抑制剂高通量筛选模型,应用该模型筛选得到了具有较好抗结核活性的丙氨酸消旋酶抑制剂。     

结核分枝杆菌Rv3203蛋白的生物信息学及免疫信息学分析

目的 运用生物信息学及免疫信息学方法分析结核分枝杆菌（Mtb）Rv3203蛋白的结构特征,为研究Rv3203蛋白在Mtb感染中的功能提供基础。方法 利用信息学软件分别预测Rv3203蛋白的理化性质、溶解度、跨膜区、信号肽、亚细胞定位、糖基化位点、磷酸化位点、相互作用蛋白、免疫原性、抗原性、毒性、致敏性,以及T、B细胞抗原表位和二级结构,并对蛋白的三级结构进行建模,最后对Rv3203蛋白进行密码子优化、计算机克隆和构建进化树。结果 Rv3203蛋白由224个氨基酸组成,理论等电点为4.68,为结构稳定的弱疏水性蛋白;无跨膜区和信号肽,定位于细胞质,具有1个糖基化位点和11个磷酸化位点;与lipD、lipE、lipP、lipZ、amiB2、amiC、bpoC、Rv0183、Rv1367c和Rv3204发生相互作用,参与Mtb的多种生物学过程;免疫原性为3.4211,抗原性为0.6533,无毒性,无致敏性;含5个CTL表位、1个Th表位和4个B细胞表位;二级结构和三级模型含大量的α-螺旋和无规则卷曲;经密码子优化后可在大肠杆菌中克隆并高效表达;此外,Mtb的Rv3203蛋白还与Mycobacterium canettii CIPT 140010059具有高度同源性。结论 Rv3203蛋白是一个结构稳定且具有热稳定性的酸性蛋白,具有免疫原性和抗原性,无毒性和致敏性,含多个T/B细胞表位,可在体外克隆并高效表达,参与Mtb的多种生物学过程及调控宿主的免疫应答反应。     

结核分枝杆菌毒力分泌基因Rv3872重组卡介苗的构建及表达

目的:构建结核分枝杆菌Rv3872的原核重组表达质粒pET-3872并对其进行表达及鉴定。构建表达结核分枝杆菌抗原蛋白Rv3872即PE35的重组卡介苗。方法:应用PCR技术扩增Rv3872基因,定向克隆入pET32a(+)并转化E.coli BL21(DE3)菌株,测序后用IPTG诱导蛋白表达,通过SDS-PAGE和Western blot对目的蛋白进行检测及鉴定。用纯化蛋白免疫新西兰大白兔制备多克隆抗体。构建重组穿梭表达质粒pMV-3872,将重组质粒电穿孔进入卡介苗,对重组卡介苗进行诱导表达用SDS-PAGE和Western blot检测和鉴定目的蛋白。结果:表达融合蛋白的pET-3872质粒构建成功,重组蛋白经Western blot检测出特异性阳性信号。重组卡介苗BCG-3872构建成功,热诱导表达后经SDS-PAGE和Western blot,在培养上清中检测到目的蛋白。结论:成功构建了重组质粒pET32a(+),并在大肠杆菌中表达了PE35蛋白,有利于进一步研究Rv3872基因功能。本研究还对表达结核分枝杆菌蛋白PE35的重组卡介苗进行了鉴定,为进一步研究该重组卡介苗的免疫功能奠定了基础。     

结核分枝杆菌Rv3881c抗原鼠单克隆抗体的制备及初步鉴定

目的:制备抗结核分枝杆菌Rv3881c抗原鼠mAb。方法:采用杂交瘤技术,获得了11株针对结核分枝杆菌Rv3881c抗原鼠mAb杂交瘤细胞株,对其中的5株进行了小鼠腹水的制备及相关鉴定。结果:5株mAb的腹水效价达到1∶32 000～1∶512 000,将这5株mAb进行了纯化,纯化后纯度大于90%,抗体亚类(型)均为IgG1/κ型,ELISA结果显示制备的mAb与结核分枝杆菌Rv3881c抗原可发生特异反应。结论:制备了抗结核分枝杆菌Rv3881c抗原鼠mAb,为结核分枝杆菌Rv3881c生物学功能的研究奠定基础。     

结核分枝杆菌CYP143A1基因(Rv1785c)敲除菌株的构建

目的 为深入了解和探索结核分枝杆菌CYP143A1基因(Rv1785c)功能,构建针对该基因的敲除菌株.方法 采用噬菌体介导的基因敲除技术,设计并采用聚合酶链反应(PCR)扩增待敲除基因Rv1785c左、右臂,与p0004s质粒连接,构建同源重组质粒p0004s-△Rv1785c.再将p0004s-△Rv1785c质粒...     

以次黄嘌呤单核苷酸脱氢酶为靶点的新型抗结核药物高通量筛选模型的建立及应用

目的 建立以结核分枝杆菌次黄嘌呤单核苷酸脱氢酶为靶点的新型抗结核药物高通量筛选模型.方法 以结核分枝杆菌H37Rv基因组为模板,pBEV表达质粒为载体,将guaB2基因克隆至pBEV以构建pBEV::guaB2重组表达质粒,表达并纯化重组的结核分枝杆菌次黄嘌呤单核苷酸脱氢酶;建立以测定反应体系340 nm吸光值变化速率...     

H37Rv结核分枝杆菌蛋白脯氨酸-谷氨酸8(PE8)的表达及其兔多克隆抗体制备

目的 克隆Rv1040c结核分枝杆菌脯氨酸-谷氨酸8(PE8)基因、构建pET28a-PE8重组载体和表达纯化PE8蛋白,制备抗PE8多克隆抗体.方法 利用重组克隆技术,将PE8基因克隆至原核表达载体pET28a,测序鉴定后,转化至大肠杆菌BL21(DE3),用0.5 mmol/L异丙基-β-D-硫代吡喃半乳糖苷(IP...     

以肽脱甲酰基酶为靶点的抗结核药物高通量筛选模型的建立和应用

目的建立以肽脱甲酰基酶(PDF)为靶点的抗结核药物高通量筛选模型,应用该模型筛选得到活性微生物发酵液粗提物样品。方法以结核分枝杆菌H37Rv基因组为模板,扩增肽脱甲酰基酶的基因片段def,构建表达载体pET-28a-def,表达并纯化结核分枝杆菌PDF酶;基于PDF水解三肽底物for-Met-Ala-Ser释放出游离NH2,而游离NH2可与荧光胺反应产生荧光的原理,利用测定所产生荧光值的方法,建立高通量药物筛选模型;使用该模型对12400个微生物发酵液粗提物样品进行筛选,同时以耻垢分枝杆菌为检定菌,平板纸片法检测样品的抗菌活性,并检测所得阳性样品的细胞毒性。结果成功构建了表达载体pET-28a-def;所建立的模型稳定可行,可用于以肽脱甲酰基酶为靶点的抗结核药物的高通量筛选;用该模型对12400个微生物发酵液粗提物样品进行筛选,最终得到8个对肽脱甲酰基酶抑制活性和抗耻垢分枝杆菌活性均较好的阳性样品,阳性率0.06%;其中5个样品的细胞毒性较小。结论建立了灵敏度好、稳定性高的结核分枝杆菌肽脱甲酰基酶抑制剂高通量药物筛选模型,应用该模型所得到的阳性样品具有进一步深入研究的意义。     

以蛋白激酶A为靶点的抗结核药物高通量筛选模型的建立和应用

目的 建立以蛋白激酶 A 为靶点的抗结核药物高通量筛选模型,应用该模型筛选具有特异性酶活抑制活性的微生物发酵液粗提物样品。 方法 以结核分枝杆菌 H37Rv 基因组 DNA 为模板,扩增目的基因片段 pknA,构建表达载体 pET43.1a-pknA,在大肠杆菌中克隆表达了重组 MTB PknA 蛋白;采用三步级联的反应方法,利用还原型烟酰胺腺嘌呤二核苷酸到氧化型烟酰胺腺嘌呤二核苷酸这一反应最大吸光值波长的变化,建立和优化蛋白激酶 A 抑制剂高通量药物筛选模型。 结果 成功构建了表达载体 pET43.1a-pknA;建立了稳定灵敏,可用于靶向结核分枝杆菌蛋白激酶 A 的抗结核药物高通量筛选模型;利用该模型对4000个微生物发酵液粗提物样品进行筛选,最终得到21个抑制蛋白激酶 A 活性的阳性样品,阳性率0.53%;以耻垢分枝杆菌和海分枝杆菌为检定菌,平板纸片法检测阳性样品的抗分枝杆菌活性,然后对阳性样品的细胞毒性和酶活抑制特异性进行评价后,最终得到8个阳性样品,其中 I10AA-02916、I09AA-02717、I09AB-02729、I08AB-00801这4个阳性样品酶活抑制特异性、抗菌活性均较好,且细胞毒性较低。 结论 建立了高稳定性的以蛋白激酶 A 为靶点的抗结核药物高通量筛选模型,应用该模型所得到的发酵液阳性样品值得进一步研究。     

检测结核分枝杆菌蛋白抗原b夹心ELISA的建立及其应用

目的 建立定量检测脑脊液中结核分枝杆菌蛋白抗原b的夹心ELISA,以便用于诊断结核性脑膜炎.方法 制备抗结核分枝杆菌蛋白抗原b鼠源性单克隆抗体(mAb)及兔多克隆抗体;以单克隆抗体为包被抗体,多克隆抗体为检测抗体,建立检测结核分枝杆菌蛋白抗原b的双抗体夹心ELISA;应用此方法检测正常人(n=6)、非结核性脑膜炎患者(n=26)及临床确诊结核性脑膜炎患者(n=42)的脑脊液标本中蛋白抗原b的含量,并分析其与结核性脑膜炎活动性感染的相关性.结果 成功建立了检测蛋白抗原b的夹心ELISA,敏感度可达0.4 μg/L.应用该方法在正常人及非结核性脑膜炎患者脑脊液中未检测到蛋白抗原b;在结核性脑膜炎患者脑脊液中蛋白抗原b含量显著升高.结论 建立了敏感、特异检测结核分枝杆菌蛋白抗原b含量的ELISA,为活动性结核性脑膜炎的诊断提供一种有效手段.     

快速检测结核分枝杆菌异烟肼和利福平耐药相关基因mPCR-SSCP建立及应用

目的 建立快速检测结核分枝杆菌异烟肼(INH)和利福平(RFP)耐药相关基因katG、inhA和rpoB突变的多重聚合酶链反应-单链构象多态性(multi PCR-single strand conformational polymorphism analysis,mPCR-SSCP)方法.方法 药敏试验检测134株结核分枝杆菌临床菌株对INH和RFP的耐药性.设计结核分枝杆菌INH和RFP耐药相关katG、inhA和rpoB基因PCR引物,建立mPCR-SSCP技术检测上述菌株katG、inhA和rpoB基因的突变,同时采用PCR直接测序技术(PCR-DS)检测上述基因片段突变情况,并对上述3种方法检测结果进行分析和比较.结果 134株临床菌株均含有katG、inhA和rpoB基因,其中42株(31.3％)对INH耐药、45株(33.6％)对RFP耐药.mPCR-SSCP和PCR-DS检测结果显示,92株INH敏感菌株katG和inhA基因均未发生突变,检测特异性均为100％;89株RFP敏感菌株中rpoB基因分别有2株和1株检测出突变,检测特异性分别为97.8％和98.9％;42株INH耐药菌株中分别有33株和36株katG和/或inhA基因突变,检测灵敏度分别为78.6％和85.7％;45株RFP耐药菌株中rpoB基因分别有41株和43株发生突变,检测灵敏度分别为91.1％和95.6％.结论 本研究建立的mPCR-SSCP能快速、简便、特异,并有一定的敏感性检测结核分枝杆菌异烟肼和利福平耐药相关基因katG、inhA和rpoB突变,具有临床应用前景.     

Assessment of in vitro immunity to Mycobacterium tuberculosis in a human peripheral blood infection model using a luciferase reporter construct of M. tuberculosis H37Rv

Protective immune responses to tuberculosis in man are primarily cell-mediated and require the interaction of specific T cells, cytokines and activated macrophages. In the present study, Mycobacterium tuberculosis H37Rv labelled with luciferase reporter enzyme was used to analyse the anti-mycobacterial immunity in man using an in vitro whole blood infection model. Peripheral blood samples obtained from M. bovis bacille Calmette-Guérin (BCG)-vaccinated tuberculin-positive healthy volunteers (n = 23) were cultured with M. tuberculosis H37Rv reporter strain. The growth of bacteria in the whole blood cultures was monitored after 48 and 96 h of infection. The results showed that the growth of M. tuberculosis was significantly inhibited after 96 h (P < 0.029) of culture. Among the cytokines studied, interleukin (IL)-10 and IL-12 were not detected at all, whereas low levels of interferon (IFN)-gamma after 96 h (0.4 IU/ml) and tumour necrosis factor (TNF)-alpha after 48 (135 pg/ml) and 96 h (47 pg/ml) of culture were detected in the supernatants of whole blood infected with M. tuberculosis. The magnitude of bacterial growth correlated directly with the concentration of TNF-alpha detected after 48 h (r = 0.722) and 96 h (r = 0.747) of culture (P 相似文献   

Expression of Mycobacterium tuberculosis MPT64 in recombinant Myco. smegmatis: purification, immunogenicity and application to skin tests for tuberculosis

Proteins secreted across the cell wall of mycobacteria are important antigens recognized early in the host response to mycobacterial infection. MPT64 is a 23-kD secreted protein restricted to members of the Mycobacterium tuberculosis complex which elicits T cell responses and cutaneous DTH reactions in Myco. tuberculosis-infected animals. Patients with tuberculosis and their tuberculin-positive contacts respond to the protein, but recipients of bacille Calmette–Guérin (BCG) vaccine strains lacking the mpt64 gene do not. In the present study, we describe the development of a unique recombinant mycobacterial vector which secretes the encoded Myco. tuberculosis protein MPT64 at high levels into the culture filtrate, from which the protein is isolated by a single-step affinity chromatographic step. The purified protein was recognized by both polyclonal and monoclonal anti-MPT64 antibodies. The T cell reactivity of the protein was confirmed by its ability to stimulate human anti-rMPB64 T cell lines. The Myco. smegmatis recombinant MPT64 protein was superior to the Escherichia coli rMPB64 protein, which has identical amino acid sequence, in eliciting cutaneous DTH reactions in guinea pigs sensitized with Myco. tuberculosis. Animals sensitized with BCG strains lacking the mpb64 gene failed to respond to MPT64. Similarly, interferon-gamma (IFN-γ) responses in tuberculosis patients and their contacts were higher to the Myco. smegmatis form of the protein. The potential of this form of the Myco. tuberculosis MPT64 protein as a skin test reagent for tuberculosis is discussed.     

Microarray analysis of the in vitro granulomatous response to Mycobacterium tuberculosis H37Ra

Background:

The hallmark of tuberculosis is the granuloma, an organized cellular accumulation playing a key role in host defense against Mycobacterium tuberculosis. These structures sequester and contain mycobacterial cells preventing active disease, while long term maintenance of granulomas leads to latent disease. Clear understanding on mechanisms involved in granuloma formation and maintenance is lacking.

Objective:

To monitor granuloma formation and to determine gene expression profiles induced during the granulomatous response to M. tuberculosis (H37Ra).

Methods:

We used a previously characterized in vitro human model. Cellular aggregation was followed daily with microscopy and Wright staining for 5 days. Granulomas were collected at 24 h, RNA extracted and hybridized to Affymetrix human microarrays.

Results:

Daily microscopic examination revealed gradual formation of granulomas in response to mycobacterial infection. Granulomatous structures persisted for 96 h, and then began to disappear.

Conclusions:

Microarray analysis identified genes in the innate immune response and antigen presentation pathways activated during the in vitro granulomatous response to live mycobacterial cells, revealing very early changes in gene expression of the human granulomatous response.     

Mycobacterium bovis with different genotypes and from different hosts induce dissimilar immunopathological lesions in a mouse model of tuberculosis

With the hypothesis that genetic variability of Mycobacterium bovis could influence virulence and immunopathology, five M. bovis strains were selected from an epidemiological study in Argentina on the basis of their prevalence in cattle and occurrence in other species. We then determined the virulence and the immunopathology evoked by these strains in a well‐characterized mouse model of progressive pulmonary tuberculosis. The reference strain AN5 was used as a control. BALB/c mice infected with this M. bovis reference strain showed 50% survival after 4 months of infection, with moderate bacillary counts in the lung. Two weeks after inoculation, it induced a strong inflammatory response with numerous granulomas and progressive pneumonia. In contrast, strain 04‐303, isolated from a wild boar, was the most lethal and its most striking feature was sudden pneumonia with extensive necrosis. Strain 04‐302, also isolated from wild boar but with a different spoligotype, induced similar pathology but to a lesser extent. In contrast, strains 534, V2 (both from cattle) and 02‐2B (from human) were less virulent, permitting higher survival after 4 months of infection and limited tissue damage. Strain AN5 and the cattle and human isolates induced rapid, high and stable expression of interferon (IFN)‐γ and inducible nitric oxide synthase (iNOS). In contrast, the more virulent strains induced lower expression of IFN‐γ, tumour necrosis factor‐α and iNOS. Interestingly, these more virulent strains induced very low expression of murine beta defensin 4 (mBD‐4); whereas, the control strain AN5 induced progressive expression of this anti‐microbial peptide, peaking at day 120. The less virulent strains induced high mBD‐4 expression during early infection. Thus, as reported with clinical isolates of M. tuberculosis, M. bovis also showed variable virulence. This variability can be attributed to the induction of a different pattern of immune response.     

Mycobacterium tuberculosis and the intimate discourse of a chronic infection

Mycobacterium tuberculosis is an extremely successful pathogen that demonstrates the capacity to modulate its host both at the cellular and tissue levels. At the cellular level, the bacterium enters its host macrophage and arrests phagosome maturation, thus avoiding many of the microbicidal responses associated with this phagocyte. Nonetheless, the intracellular environment places certain demands on the pathogen, which, in response, senses the environmental shifts and upregulates specific metabolic programs to allow access to nutrients, minimize the consequences of stress, and sustain infection. Despite its intracellular niche, Mycobacterium tuberculosis demonstrates a marked capacity to modulate the tissues surrounding infected cells through the release of potent, bioactive cell wall constituents. These cell wall lipids are released from the host cell by an exocytic process and induce physiological changes in neighboring phagocytes, which drives formation of a granuloma. This tissue response leads to the generation and accumulation of caseous debris and the progression of the human tuberculosis granuloma. Completion of the life cycle of tuberculosis requires damaging the host to release infectious bacteria into the airways to spread the infection. This damage reflects the pathogen's ability to subvert the host's innate and acquired immune responses to its own nefarious ends.     

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.