应用特异性引物鉴定人申克孢子丝菌感染

目的研究人申克孢子丝菌感染的分子生物学鉴定方法,为建立检测人申克孢子丝菌感染的快速、敏感、特异方法提供参考资料。方法从疑似申克孢子丝菌感染患者的感染部位表面刮取物、腐烂组织或活检组织中提取DNA,应用合成的申克孢子丝菌特异性引物ITS3-SSP进行核糖体DNA内1332靶序列PCR扩增,将检测结果与真菌培养鉴定结果或组织病理学检查对比,观察种特异性引物PCR扩增结果的敏感性和特异性。结果在17例经形态学检查和／或真菌培养检查证实的组织标本中,有12例扩增出191bp的片段,其中7例组织中发现染成紫红色的圆形或卵圆形的孢子;而在11例经真菌培养证实为申克孢子丝菌的标本中,有4例样品巢式PCR结果为阴性。结论应用所设计的特异性引物ITS3-SSP结合巢式PCR方法鉴定申克孢子丝菌特异、敏感,是一种非常有发展潜力的检查手段。     

巢式聚合酶链式反应检测脑脊液标本中病原体的方法评价

目的探讨巢式聚合酶链式反应(PCR)检测脑脊液标本中病原体的可行性,为疾病的快速临床诊断提供参考。方法源自细菌16S rRNA基因序列设计的巢式PCR技术方法,包括2对引物,2次PCR扩增,第1对引物首次PCR扩增脑脊液标本提取的核酸DNA,第2对引物再次PCR扩增,其DNA模板为第1轮PCR扩增产物。将第2轮PCR扩增产物进行测序,对序列进行比对分析,从而确定感染的病原体。使用DNA微量分光光度测定布鲁氏菌纯菌核酸DNA,将DNA进行倍比稀释,用于巢式PCR敏感性测试。结果巢式PCR能够检测的最低限约为1个核酸DNA拷贝数。应用巢式PCR检测40份临床患者的脑脊液标本,扩增结果表明有37份标本获得约1 460 bp的预期扩增条带(不同细菌扩增片段有差异),测序比对结果显示,检出脑膜炎奈瑟菌7份、产碱假单胞菌1份、草假单胞菌22份、嗜麦芽窄食单胞菌2份、肺炎链球菌1份、未知细菌性病原体4份、未检出3份。结论巢式PCR能够快速检测与鉴定脑脊液标本中的细菌性病原体。     

两种分子生物学试剂检测高危型HPV

目的 对杂交捕获2代试验(hc2)与荧光聚合酶链反应(PCR)检测高危型人乳头状瘤病毒(HPV)的9例不相符结果进行验证与比对.方法 用简并引物.巢式PCR检测样本中是否存在HPV DNA;用DNA测序及反向斑点杂交法对标本中的HPV进行分型.结果 通过引物MY09/11和GPS/6进行巢式PCR扩增,9例样本扩增产物电泳后均可见清晰单一的DNA条带.DNA测序证实,在9例样本中HPV高危型3例,低危型5例,另有1例测序结果不清晰者经反向斑点杂交法检测为高危型HPV59与低危型HPV40混合感染.结论 hc2法具备较高的真阴性率,其特异性较好;荧光PCR具较高的真阳性率,其敏感性较高.     

多重巢式PCR检测恶性疟和间日疟原虫

目的建立鉴别诊断恶性疟原虫(P.f)和间日疟原虫(P.v)的多重巢式PCR法。方法针对P.f、P.v 18S rRNA基因设计外引物和内引物,优化引物浓度与退火温度,建立可扩增出两种疟原虫基因片段的多重巢式PCR,并检测54例疑似疟疾临床标本,以镜检法为金标准评价敏感性和特异性等指标。结果该方法可扩增出162 bp(P.f)和112 bp(P.v)基因片段,并能检出混合感染。该方法检测P.f,敏感性为87.50%、特异性为63.33%;检测P.v,敏感性为69.23%、特异性为68.29%。结论所建立的多重巢式PCR方法能可靠诊断疟疾并鉴别虫种,敏感性高,在混合感染的诊断方面具有优越性。     

荧光定量PCR法检测烟曲霉DNA

目的 建立检测烟曲霉DNA的荧光定量PCR方法,评价其在小鼠侵袭性烟曲霉肺部感染诊断中的意义.方法 根据烟曲霉ITSI区域基因组序列,设计合成引物和荧光标记探针,优化荧光定量PCR条件,从特异性、扩增效率、灵敏度及重复性方面进行评价.建立小鼠烟曲霉肺部感染模型,用荧光定量PCR对36只实验小鼠肺组织及支气管肺泡灌洗液(...     

应用巢式PCR检测孕妇血浆中cffDNA RHD基因型的研究

目的建立巢式PCR技术检测RhD阴性孕妇血浆中游离胎儿DNA(cffDNA)的RHD基因型,以预测胎儿RhD血型。方法采用QIAamp DNA Blood Mini Kit提取32例RhD阴性孕妇血浆游离DNA,针对RHD外显子7和10分别设计外侧、内侧2组特异性引物,巢式PCR方法检测孕妇血浆游离胎儿DNA的RHD型,测序验证PCR产物的序列特异性。结果孕妇血浆游离DNA经巢式PCR扩增后,有27例成功扩增出RHD外显子7、10特异性条带,5例未检测到RHD基因特异性扩增,32例中有30例胎儿RHD型与出生后血型相符,检测准确率为93.1%。结论采用巢式PCR技术检测RhD阴性孕妇血浆游离胎儿DNA来判定胎儿RHD型,具有良好的准确性、敏感性和特异性,为RhD新生儿溶血病的早期诊断提供了一种新的、可靠的检测手段。     

两种分子生物学试剂检测高危型HPV不相符结果的验证分析

目的对杂交捕获2代试验（hc2）与荧光聚合酶链反应（PCR）检测高危型人乳头状瘤病毒（HPV）的9例不相符结果进行验证与比对。方法用简并引物-巢式PCR检测样本中是否存在HPVDNA；用DNA测序及反向斑点杂交法对标本中的HPV进行分型。结果通过引物MY09／11和GP5／6进行巢式PCR扩增．9例样本扩增产物电泳后均可见清晰单一的DNA条带。DNA测序证实，在9例样本中HPV高危型3例，低危型5例，另有1例测序结果不清晰者经反向斑点杂交法检测为高危型HPV59与低危型HPV40混合感染。结论hc2法具备较高的真阴性率，其特异性较好；荧光PCR具较高的真阳性率，其敏感性较高。     

巢式聚合酶链式反应检测布鲁氏菌核酸DNA方法的建立

目的建立一种具有灵敏性高,特异性强的巢式聚合酶链式反应(PCR)方法检测血液标本中布鲁氏菌核酸DNA。方法使用细菌基因组提取试剂盒提取纯菌核酸DNA;使用血液等组织基因组核酸DNA提取试剂盒提取血液标本核酸DNA,对提取的核酸DNA先行常规PCR预扩增,以扩增的PCR产物为模板进行荧光定量PCR第二次扩增(即巢式PCR)。对纯菌提取的核酸DNA进行灵敏度和和特异性测试,构建巢式PCR的Ct值与核酸DNA拷贝数之关系曲线;检测临床血液标本核酸DNA,同时比较常规两种PCR方法检测结果。结果常规PCR检测的灵敏度为512个核酸DNA拷贝数;巢氏PCR检测有效范围为921.6 ng/μl^6.8 fg/μl,对应的Ct值为12.04~37.50,其指数关系为:y=(e-0.695x)×1012;R2=0.9986,巢式PCR扩增效率为2.28×109倍,检测限为2个布鲁氏核酸DNA拷贝数。巢式PCR的灵敏度为91.67%,特异度为93.10%,阳性预测值为91.67%,阴性预测值为93.10%。对一起羊养殖场采集的25份血液标本应用巢式PCR方法检测,结果阳性率为92.00%(23/25);27份健康人群血液标本没有检测出(无Ct值)。结论巢式PCR具有较好的灵敏性和特异性,特别适合于血液标本布鲁氏菌核酸DNA的检测。     

DNA微列阵技术检测戊型肝炎病毒方法的建立及初步应用

目的建立DNA微列阵技术检测戊型肝炎病毒方法,进而探讨该方法用于检测临床标本的可行性。方法通过生物医学数据库戊型肝炎病毒基因进行检索和筛选,应用分子生物学软件,进行序列分析、引物及探针设计,并进行验证,建立了戊型肝炎病毒DNA微列阵技术检测方法。结果试验所设计的探针仅与HEV的PCR产物杂交呈阳性,与乙肝、丙肝等对照病毒的PCR产物杂交呈阴性。敏感性试验显示,该方法比同巢式PCR方法检测戊型肝炎病毒敏感度要高,用该方法检测了长春地区50份疑似HEV临床病料,38份阳性;而用巢式PCR法扩增HEV ORF1基因确诊为阳性的只有35份。结论利用DNA微列阵技术检测戊型肝炎病毒方法,特异性和敏感性强,可作为HEV临床标本检测方法。     

三种食源性致病菌多重PCR检测方法的建立及初步应用

目的建立快速检测沙门菌、变形杆菌和金黄色葡萄球菌的多重聚合酶链反应(PCR)方法。方法本研究依据沙门菌侵袭基因正调节蛋白(hilA)基因、变形杆菌溶血素(hpmA)基因和金黄色葡萄球菌特异性pSa-442序列,运用Primer Premier 5.0分别设计3对特异性引物,预计PCR扩增的目的基因片段分别为为580bp、401 bp、256 bp。通过对单管多重PCR扩增的特异性、敏感性分析以及建立L16(43)正交试验对单管多重PCR扩增条件如引物浓度、dNTP浓度和Tm值等的优化,建立了快速同时检测3种食源性致病菌的单管多重PCR方法。结果该方法检测的灵敏度分别为:94.07 pg沙门菌DNA,140.85 ng变形杆菌DNA,1.41 ng金黄色葡萄球菌DNA。模拟检测食品中的混合3种菌,4 h培养后样品的最低检测限度分别为:沙门菌100菌落形成单位(CFU)/mL、变形杆菌101CFU/mL、金黄色葡萄球菌100CFU/mL。结论该方法特异性和灵敏度高,检验周期短,可用于对食品中多种致病菌的快速诊检和监控。     

Evaluating a semi‐nested PCR to support histopathology reports of fungal rhinosinusitis in formalin‐fixed paraffin‐embedded tissue samples

BackgroundFungal rhinosinusitis (FRS) encompasses a various spectrum of diseases. Histopathology is the “reference method” for diagnosing FRS, but it cannot determine the genus and species. Moreover, in more than 50% of the histopathologically proven cases, the culture elicited no reliable results. This study was an attempt to evaluate the diagnostic efficiency of semi‐nested polymerase chain reaction (PCR) from formalin‐fixed paraffin‐embedded (FFPE) functional endoscopic sinus surgery (FESS) in FRS patients.MethodsOne hundred ten specimens were subjected to DNA extraction and histopathology examination. The amplification of the β‐globin gene by conventional PCR was used to confirm the quality of extracted DNA. The semi‐nested PCR was performed using ITS1, ITS2, and ITS4 primers during two steps. Sequencing the internal transcribed spacer region (ITS1‐5.8S‐ITS2) to identify causative agents was performed on PCR products.ResultsSixty‐four out of 110 samples were positive by histopathology evidence, of which 56 samples (87.5%) were positive by PCR. Out of 46 negative samples by histopathological methods, five samples (10.9%) yielded positive results by PCR. Sensitivity, specificity, positive predictive value, and negative predictive value of the semi‐nested PCR method were reported 87.5%, 89.2%, 92.7%, and 85.2%, respectively. The kappa factor between PCR and histopathological methods was 0.76, indicating substantial agreements between these two tests.ConclusionDue to the acceptable sensitivity and specificity of the present method, it might be used to diagnose fungal sinusitis infections along with microscopic techniques. This method is recommended to confirm the diagnose of suspected fungal sinusitis with negative histopathology results.     

实时荧光定量PCR检测血中曲霉菌基因的实验研究

目的：建立并评价从血标本中检测曲霉菌基因的real-time PCR方法。方法：用自行设计的高效率引物探针对标准菌株及临床疑似病人血标本进行检测,对方法的敏感性、特异性进行评价。结果检测出曲霉菌基因敏感性达10拷贝ITS I基因,相当于5～10CFU／ml,与人类基因组、其他真菌及细菌无交叉反应。29例临床疑似标本阳性率为69％,与临床诊断符合率为86％。结论：real-time PCR检测血中曲霉菌基因有较高的敏感性、特异性,有一定的临床应用前景。     

Detection and identification of Candida spp. in human serum by LightCycler real-time polymerase chain reaction

The aim of this work was to develop LightCycler real-time polymerase chain reaction method to allow rapid detection and identification of Candida spp. in human serum with panfungal primers (internal transcribed spacer [ITS] and L18). Melting-curve analysis of the ITS sequences showed that each amplicon presented a specific melting point and enabled identification of 5 Candida spp. After parameters optimization, 58 sera were preliminary analyzed from 23 patients. For L18 primers, the LightCycler system enabled detection of DNA in 92% of patients with positive blood culture. These primers were not able to differentiate between species of Candida. By using ITS primers, the LightCycler system enabled detection of DNA in sera from 76.9% of patients with positive blood culture. With ITS primers, the species responsible for the infection was identified for 11 patients. These data revealed the LightCycler as a potential tool for early detection and identification of Candida.     

聚合酶链反应检测SEN病毒D亚型方法的建立

目的：研究建立SEN病毒D亚型（SENV－D）聚合酶链反应（PCR）检测方法。方法：选择SENV－D开放读码框1高度保守序列，设计合成2对特异性引物，建立检测SENV－D感染的套式PCR方法。对327例无偿献血和职业献血者进行SENV感染的检测，并对部分PCR阳性产物进行克隆测序，结果：该方法特异性和灵敏度均较高，检测结果显示无偿献血人群SENV－D感染率为5．5％，职业献血人群为6．7％，两者无统计学差异，结论：我国广东部分地区无偿献血和职业献血人群中存在SENV－D亚型感染；建立的该方法适用于SENV感染的检测。     

Identification of Actinobacillus pleuropneumoniae biovars 1 and 2 in pigs using a PCR assay

Actinobacillus pleuropneumoniae causes swine pleuropneumonia worldwide. Previously, we described a gene sequence of approximately 800bp in A. pleuropneumoniae serotype 1 that encodes a metalloprotease of 24kDa, (Genbank accession no. AY217757). We selected primers carrying the forward and reverse 5'-terminal sequences of this region of the gene for the development of a species-specific PCR assay. The primers amplified an 800bp sequence from isolated DNA and lysed bacteria of the 13 A. pleuropneumoniae biovar 1 serotypes, with the exception of subtype 1b. The primers also amplified the sequence in nasal secretion cultures from pigs with chronic and acute experimental pleuropneumonia. No PCR products were detected when A. pleuropneumoniae serotypes of biovar 2 were used. Internal primers from this gene sequence detected biovar 2 and subtype 1b, leading to the production of a 350bp PCR product. The primers did not amplify DNA from other related species from the Pasteurellaceae family. The 800bp PCR assay was sensitive in vitro, with a detection limit of 5.5pg of extracted DNA, and an average of 120CFU. The specificity and sensitivity of this PCR assay make it a useful method for the rapid identification and diagnosis of A. pleuropneumoniae.     

The utility of cerebrospinal fluid for the molecular diagnosis of toxoplasmic encephalitis

The aim of this study was to assess the efficacy of nested polymerase chain reaction (PCR) and the loop-mediated isothermal amplification (LAMP) assay, which were developed to detect and identify toxoplasma parasites in human cerebrospinal fluid (CSF). Nested PCR was performed using primers generated by Dr. L.D. Sibley to target the 18S rDNA instead of the conventionally used primers which target the B1 gene. We also designed Toxoplasma gondii–specific LAMP primers targeting both genes. In vitro detection sensitivity was evaluated using 10-fold serially diluted genomic DNA purified from RH tachyzoites, and clinical sensitivity and specificity were evaluated using clinical CSF samples from 16 patients with toxoplasmic encephalitis (TE) and from 12 patients with other diseases. The 18S rDNA nested PCR showed the highest detection sensitivity limit with a minimum of 1.0 × 10⁻⁸ ng/μL. However, sensitivity and specificity of nested PCR with clinical specimens were 50% and 100%, respectively. The sensitivity of molecular diagnosis of TE is not sufficient; therefore, patients clinically suspected of having TE should be treated promptly. Our molecular diagnostic tool would restrictively facilitate a definitive diagnosis of TE at an early stage in approximately 50% of patients.     

PCR detection of Giardia lamblia in stool: targeting intergenic spacer region of multicopy rRNA gene

A PCR based detection that amplifies the 552-bp intergenic spacer (IGS) region of multicopy rRNA gene of Giardia lamblia and 320-bp internal sequences to first PCR product has been used in diagnosis of giardiasis in stool sample. The primers were found highly specific to Giardia spp. only, because no amplification was observed with DNAs from other enteric pathogens like Escherichia coli, Shigella dysenteriae and Entamoeba histolytica. The test could detect even less than 2 pg of genomic DNA from Giardia trophozoites. In direct diagnosis of Giardia lamblia in stool samples, it was observed that PCR amplification of IGS followed by nested PCR could enhance the sensitivity and specificity of the tests manifold and the system was able to detect as low as 10 parasites in 100 microl of stool. The comparative evaluation of the present system with conventional microscopy, CIEP and ELISA in the diagnosis of giardiasis from diarrhoeic stool samples and control subjects demonstrated a 100% correlation among nested PCR, microscopic examination and ELISA in patients suggestive of giardiasis (Group I) and control subjects (Group II). In Group I cases (patients suffering from other than giardiasis), CIEP, ELISA and nested PCR showed better results than microscopic examination. However, among them, PCR was found most sensitive and specific because 20% positivity was noticed by PCR whereas CIEP and ELISA showed only 7.14% and 12.85%, respectively. Break-up results showed that all the samples which were positive by CIEP or ELISA, also found positive by PCR. The present observation clearly suggests the use of PCR that amplifies the intergenic spacer region of multicopy rRNA gene of Giardia lamblia followed by nested PCR for routine, quick and reliable detection of Giardia lamblia in stool samples.     

The development and evaluation of a nested PCR assay for detection of Neospora caninum and Hammondia heydorni in feral mouse tissues

The development of a novel nested polymerase chain reaction is described and used for detecting the presence of Neospora caninum and Hammondia heydorni DNA in DNA extracted from feral rodent tissues. A unique strategy was used for design of an assay that could be adapted for detecting DNA from more than one member of Toxoplasmatinae simultaneously with a minimal number of additional steps. The level of sensitivity described for this assay is comparable to real time-PCR and other nested PCR assays. Twenty-eight of 104 feral mice tested positive for N. caninum in at least one tissue (the brain, heart or liver) studied. In this study, eight instances are reported where the brain tested negative to N. caninum while at least one other tissue was positive. This suggests that prior studies, which screened only the brain, describe prevalence levels that are under-represented. None of 54 mouse brains tested positive for H. heydorni DNA. This suggests that mice are rarely infected by H. heydorni although this hypothesis needs to be explored further. Data obtained in the current study suggest that N. caninum is a common parasite of feral rodents which may be important in the epidemiology of the disease.