实时定量PCR检测马传染性贫血病毒载量方法的建立和应用

目的建立实时定量PCR检测血浆病毒载量的方法，对马传染性贫血病毒（equine infectious anemia virus，EIAV）强毒株攻毒马和疫苗免疫攻毒马血浆中病毒载量进行了跟踪检测，探讨病毒载量和临床疾病状态的相关性。方法以EIAV强毒株LN40序列为标准，在gag保守区设计1对引物和Taqman探针，用于实时定量PCR扩增，用含扩增目的基因的体外转录RNA作标准品，获得标准曲线，对扩增样品进行准确定量。强毒株LN40直接攻毒，或者疫苗株DLV免疫马6个月后用强毒株LN40进行攻毒，跟踪检测攻毒马及免疫攻毒马血浆中EIAV载量情况。结果反应在10^1～10^9copies／ml之间具有良好的线性关系，反应的检出下限为10copies／ml。强毒攻毒马出现发热并最终死亡，发热期间马血浆中EIAV载量与体温呈正相关，载量最高达10^7copies／ml。免疫攻毒马未出现发热，其血浆EIAV载量的总体水平低于强毒攻毒马，攻毒后3个月低至10copies／ml以下。结论成功建立了实时定量PCR检测血浆EIAV载量的方法，并证实了用实时荧光定量PER检测EIAV病毒载量的方法来监测动物感染状态具有可行性，为EIAV致病机制研究和弱毒疫苗免疫保护机制的研究提供良好的技术平台。     

荧光定量PCR用于重组杆状病毒鉴定及病毒滴度检测的研究

目的：建立一种高效、简便的荧光实时定量PCR方法,用于重组杆状病毒鉴定及病毒滴度的检测.方法：利用Bac-to-Bac载体系统在E.coli菌株DH10 Bac中构建重组杆状病毒穿梭质粒（Bacmid）和在昆虫细胞中构建含人IL-18基因的重组杆状病毒,纯化的重组Bacmid作为PCR检测的标准模板,由昆虫细胞中收获的病毒母液用于空斑测定和病毒DNA提取.以10倍梯度稀释的重组Bacmid作为标准模板,进行荧光定量PCR扩增IL18基因片段并绘制标准曲线,然后以提取的重组杆状病毒DNA作为模板,采用同样体系进行实时PCR反应检测.同时,以琼脂糖空斑法测定病毒母液的滴度.结果：成功构建了重组杆状病毒并建立了病毒滴度的实时荧光PCR检测方法.运用标准模板进行的PCR反应显示该方法的线形范围为101～108拷贝,病毒母液的DNA拷贝浓度（vg/ml）值约为空斑检测的滴度pfu/ml值的10倍.结论：荧光定量PCR方法可灵敏快速地鉴定重组杆状病毒,并在较大的线性范围内检测重组杆状病毒滴度,较之空斑法更准确地反映了重组杆状病毒的实际数量.     

利用重组痘苗病毒表达人CD20基因

目的获得重组人 CD2 0分子并研究编码人 CD2 0的基因在痘苗病毒中的表达。方法从 p GEM- T- EASY/ CD2 0载体上酶切下编码人 CD2 0分子的 c DNA,亚克隆到 p JSA1175载体上 ,重组质粒与野生痘苗病毒共转染 TK- 143细胞。结果APAAP检测到重组病毒感染的细胞表面有 CD2 0分子表达 ,富集后病毒滴度约为 1× 10 9pfu/ ml。结论人 CD2 0基因在痘苗病毒中表达 ,为研究其功能以及研制单克隆抗体奠定了基础     

实时荧光定量PCR检测转基因小鼠外源基因拷贝数方法的建立和应用

目的建立实时荧光定量PCR方法检测CaMKⅡα-Cre转基因小鼠外源基因拷贝数的方法。方法以CaMKⅡα-Cre转基因首建鼠及其仔代阳性鼠为研究对象,利用绝对定量的实时荧光定量PCR法检测转基因小鼠的拷贝数,并筛选出纯合子小鼠再经遗传育种方法以确定为纯合子小鼠。结果绝对定量标准曲线公式为:△Ct=-2.402log5N(拷贝数)+8.654,相关系数为0.9999,扩增效率为95.4%。三只CaMKⅡα-Cre首建鼠的拷贝数分别为19、7、5;三个转基因小鼠品系均成功获得纯合子小鼠。结论成功建立了检测转基因小鼠外源基因拷贝数的实时荧光定量PCR方法,该方法可用于检测各种转基因小鼠中外源基因的拷贝数。     

实时荧光定量PCR的应用体会

对于病毒的监测和疾病的诊断,定性检测已不能满足临床需要,实时荧光定量PCR技术(realtime quantitative PCR)于1996年由美国Aplied Biosystems公司推出.     

实时定量PCR技术在病毒学研究中的应用

近年来发展起来的实时定量PCR技术与传统PCR技术相比,具有灵敏度和特异性高、重复性好、检测范围宽的优点,且极大降低了交叉污染的可能性。广泛应用于病毒感染的定量检测、临床疗效和药物评价、感染人群的普查以及感染源的监测、病毒与疾病之间关系的研究等方面。     

荧光定量PCR用于重组杆状病毒鉴定及病毒滴度检测的研究

目的：建立一种高效﹑简便的荧光实时定量PCR方法，用于重组杆状病毒鉴定及病毒滴度的检测。方法：利用Bac-to-Bac载体系统在昆虫细胞中构建含人IL-18基因的重组杆状病毒，收获的病毒母液以10倍梯度系列稀释后，提取病毒基因组DNA。以10倍梯度稀释的重组杆状病毒穿梭质粒（bacmid）作为标准模板，进行荧光定量PCR反应扩增IL-18基因片段并绘制标准曲线，然后以上述的重组杆状病毒基因组DNA作为模板，采用同样体系进行实时PCR反应检测，同时用琼脂糖空斑法测定病毒母液的滴度。结果：成功构建了重组杆状病毒并建立了病毒滴度的实时荧光PCR检测方法。运用标准模板进行的PCR反应显示该方法的线形范围为101-108拷贝，病毒母液的DNA拷贝浓度（vg/mL）值约为空斑检测的滴度 pfu/mL值的10倍。结论：荧光定量PCR方法可灵敏快速地鉴定重组杆状病毒，并在较大的线形范围内检测重组杆状病毒滴度，较之空斑法更准确地反映了重组杆状病毒的实际数量。     

实时定量PCR技术在病毒学研究中的应用

近年来发展起来的实时定量PCR技术与传统PCR技术相比，具有灵敏度和特异性高、重复性好、检测范围宽的优点，且极大降低了交叉污染的可能性。广泛应用于病毒感染的定量检测、临床疗效和药物评价、感染人群的普查以及感染源的监测、病毒与疾病之间关系的研究等方面。     

实时荧光定量PCR检测幼儿腹泻腺病毒

目的:建立实时荧光定量PCR方法,并检测腺病毒Ad40或Ad41感染的粪便标本。方法:用T-A克隆技术构建含腺病毒基因的载体作为标准模板,采用Taqman探针标记技术,建立实时荧光定量PCR方法。采集幼儿腹泻标本248例,分别用直接免疫荧光法和实时荧光定量PCR检测腺病毒Ad40和Ad41,比较两种方法的阳性检出率。结果:实时荧光定量PCR灵敏度和准确度(95.60%和96.80%)均高于直接免疫荧光法(78.5%和82.40%)(P0.05),而两者特异度差异无统计学意义(97.30%vs 96.70%,P0.05)。248例待检样本,直接免疫荧光法检出率为2.42%(6/248),实时荧光定量PCR检出率为7.66%(19/248),明显高于直接免疫荧光法(χ2=3.675,P0.05)。结论:成功建立实时荧光定量PCR检测腺病毒Ad40或Ad41方法。其灵敏度、准确度和阳性检出率经均优于直接免疫荧光法,且简便快速。     

应用实时定量PCR进行肿瘤表达研究中内参基因的选择

实时定量PCR(real-time quantitative PCR,RT-qPCR)是检测肿瘤基因表达水平的一种有效方法,在其中应用较多的相对定量方法需要一种能够在不同的组织、甚至不同的实验条件下表达恒定的理想的内参基因.但是很多研究都已经表明内参基因的表达是可变的.所以为了获得适用于肿瘤表达研究的内参基因,越来越多的研究在近期涌现出来.该文将会对近期关于肿瘤表达研究中内参基因选择的文章进行综述.     

Direct identification of recombinant vaccinia virus plaques by PCR.

A fast method for the identification of recombinant vaccinia viruses directly from individual plaques is described. Plaques are picked, resuspended in PBS-A and processed for PCR using two 'universal' primers. The amplified sequences are analyzed by agarose gel electrophoresis. This procedure allows discrimination between spontaneously arising TK-negative mutants, which do not carry the inserted gene, and the desired TK-negative recombinants resulting from insertional inactivation of the TK gene.     

Microarray assay for evaluation of the genetic stability of modified vaccinia virus Ankara B5R gene

Adverse events associated with the use of live smallpox vaccines have led to the development of a new generation of attenuated smallpox vaccines that are prepared in cultured cells as alternatives. The inability to conduct direct clinical evaluation of their efficacy in humans demands that licensure be based on animal studies and exhaustive evaluation of their in vitro properties. One of the most important characteristics of live viral vaccines is their genetic stability, including reversion of the vaccine strain to more virulent forms, recombination with other viral sequences to produce potentially pathogenic viruses, and genetic drift that can result in decrease of immunogenicity and efficacy. To study genetic stability of an immunoessential vaccinia virus gene in a new generation smallpox vaccine, an advanced oligonucleotide microchip was developed and used to assay for mutations that could emerge in B5R gene, a vaccinia virus gene encoding for a protein that contains very important neutralizing epitopes. This microarray contained overlapping oligonucleotides covering the B5R gene of modified vaccinia virus Ankara (MVA), a well-studied candidate smallpox vaccine. The microarray assay was shown to be able to detect even a single point mutation, and to differentiate between vaccinia strains. At the same time, it could detect newly emerged mutations in clones of vaccinia strains. In the work described here, it was shown that MVA B5R gene was stable after 34 passages in Vero and MRC-5 cells that were proposed for use as cell substrates for vaccine manufacture. Potentially, the proposed method could be used as an identity test and could be extended for the entire viral genome and used to monitor consistency of vaccine production.     

Quantitative assay of recombinant vaccinia virus-encoded neomycin phosphotransferase in infected eukaryotic cell lysates

A method for the detection and quantitation of neomycin phosphotransferase (NPT II) activity in recombinant vaccinia virus (VV)-infected eukaryotic cell lysates is described. The assay is linear with respect to both protein concentration and time of incubation. Cytoplasmic extracts of cells infected with a recombinant VV expressing the bacterial neo gene exhibited NPT II levels more than 50-fold higher than those detected in extracts from either uninfected or VV-infected cells. These results indicate that interference from cellular or viral-induced ATPase activities is sufficiently low that NPT II enzyme activity can be measured in crude cell lysates without employing additional protein purification procedures.     

Real-time PCR assay to identify variants of Vaccinia virus: implications for the diagnosis of bovine vaccinia in Brazil

Naturally occurring infections of Vaccinia virus (VACV) have been recognized in Brazil during the past 10 years. Human Brazilian Vaccinia virus (BVV) infections typically occur as a zoonosis transferred from affected dairy cows to their handlers. Outbreaks have caused notable economic losses to the rural community in the region. The origins of BVV are unclear but previous analyses have shown that at least two distinct clades of BVV exist. The aim of this study was to develop a rapid and inexpensive process for identification and differentiation of BVV that should facilitate epidemiological and ecological investigations including the improved diagnosis of Brazilian Orthopoxvirus infections. A SYBR green quantitative real-time polymerase chain reaction (PCR) targeting the hemagglutinin gene was developed to identify different populations of BVV, VACV vaccine strains used in Brazil during the smallpox eradication campaign (Vaccinia Lister (VACV-LIS) and New York City Board of Health (VACV-NYCBH)), and currently available vaccines (VACV-NYCBH DRYVAX and VACV-NYCBH Acambis 2000). Three primer combinations (one to amplify many orthopoxviruses including all vaccinia viruses described so far; one to differentiate BVV from vaccine strains (VACV-LIS, VACV-NYCBH DRYVAX and VACV-NYCBH Acambis 2000); and one to differentiate BVV clades) were designed to work at the same annealing temperature and reaction conditions. In addition, these methods were able to detect orthopoxvirus viral DNA in lesion biopsy material without the need for DNA extraction.     

Immunogenic properties of recombinant vaccinia virus containing the human IL-2 gene

A genetic construct of the human interleukin-2 (IL-2) gene within vaccinia virus (L-IVP strain) has been designed. The authors show the capacity of CV-1 cells infected with the recombinant vaccinia virus VV-SIL2 to secrete human IL-2 into the culture medium. Human IL-2 has been detected by immunoblotting. The sera from the animals immunized with the recombinant virus VV-SIL2 exhibited both human IL-2 and its antibodies throughout the observation period. This recombinant virus immunization induced both humoral and cell-mediated immune responses to human IL-2; the observed changes in the concentrations of cytokines are likely to suggest that the response predominantly followed a Th1 pathway. The study construct was nontoxic at the used concentrations and administration routes. The findings point that it is promising to investigate the adjuvant properties of the recombinant VV-SIL2 vaccine-based preparation for immunization in combination with various vaccines and to study this construct in therapy for cancer diseases.     

Neutralization assay using a modified vaccinia virus Ankara vector expressing the green fluorescent protein is a high-throughput method to monitor the humoral immune response against vaccinia virus

Vaccination against smallpox is again considered in order to face a possible bioterrorist threat, but the nature and the level of the immune response needed to protect a person from smallpox after vaccination are not totally understood. Therefore, simple, rapid, and accurate assays to evaluate the immune response to vaccinia virus need to be developed. Neutralization assays are usually considered good predictors of vaccine efficacy and more informative with regard to protection than binding assays. Currently, the presence of neutralizing antibodies to vaccinia virus is measured using a plaque reduction neutralization test, but this method is time-consuming and labor-intensive and has a subjective readout. Here, we describe an innovative neutralization assay based on a modified vaccinia virus Ankara (MVA) vector expressing the green fluorescent protein (MVA-gfp). This MVA-gfp neutralization assay is rapid and sensitive and has a high-throughput potential. Thus, it is suitable to monitor the immune response and eventually the efficacy of a large campaign of vaccination against smallpox and to study the vector-specific immune response in clinical trials that use genetically engineered vaccinia viruses. Most importantly, application of the highly attenuated MVA eliminates the safety concern in using the replication-competent vaccinia virus in the standard clinical laboratory.     

Expression of bovine leukaemia virus envelope gene by recombinant vaccinia viruses

Recombinant vaccinia viruses (VV) containing the envelope gene of bovine leukaemia virus (BLV) were constructed. Three virus constructs were designed: VV-BLV1 which contained the open reading frame for envelope glycoprotein gp51 alone, under control of VVP7.5 promoter; VV-BLV2 and VV-BLV3 contained the entire gene (gp51 + gp30) coding sequence downstream of VP7.5 and the fowlpox virus early/late promoter (PFE/L) respectively. All three VV recombinants expressed envelope glycoproteins as determined by the agar gel diffusion assay. By immunofluorescence techniques it was shown that while VV-BLV2 and VV-BLV3 expressed envelope glycoprotein on the surface of virus-infected cells, VV-BLV1 failed to do so. Rabbits inoculated with VV-BLV1 failed to show an anti envelope glycoprotein antibody response, however, significant levels of antibodies against envelope glycoprotein were detected in sera from rabbits inoculated with VV-BLV2 and VV-BLV3.     

表达单纯疱疹病毒Ⅱ型糖蛋白D的重组痘苗病毒活疫苗株的建立

我们以前曾报道，表达单纯疱疹病毒Ⅱ型糖蛋白Ｄ（ＨＳＶ－２ｇＤ）的重组痘苗病毒（实验疫苗株）能保护被免疫小鼠抵抗致死量ＨＳＶ－２病毒的攻击。在此工作基础上，严格按人用疫苗研究要求的实验条件，成功地建立了表达ＨＳＶ－２ｇＤ的重组痘苗病毒活疫苗株。首先将经聚合酶链反应（ＰＣＲ）修饰的ＨＳＶ－２ｇＤ基因插入痘苗表达质粒ｐＪＳＢ１１７５，置于痘苗病毒Ｐ７５Ｋ早／晚期启动子控制下。将此重组质粒用Ｌｉｐｏｆｅｃｔｉｎ方法转染已受野型ＴＫ＋痘苗病毒天坛７６１株感染的人胚肺二倍体细胞。经同位素探针（３２Ｐ－ＨＳＶ－２ｇＤ）原位杂交法和３轮蚀斑纯化，筛选出基因组内整合有ＨＳＶ－２ｇＤ基因的重组痘苗病毒。斑点和Ｓｏｕｔｈｅｒｎ杂交证实，ＨＳＶ－２ｇＤ基因已插入痘苗病毒基因组内预期的ＴＫ区段，间接免疫荧光检测显示，重组病毒感染细胞后能有效地表达ＨＳＶ－２ｇＤ蛋白。     

Species-specific identification of variola, monkeypox, cowpox, and vaccinia viruses by multiplex real-time PCR assay

A method of one-stage rapid identification of variola (VARV), monkeypox (MPXV), cowpox (CPXV), and vaccinia (VACV) viruses, pathogenic for humans, utilizing multiplex real-time TaqMan PCR (MuRT-PCR) assay was developed. Four pairs of oligonucleotide primers and four hybridization probes with various fluorescent dyes and the corresponding fluorescence quenchers were concurrently used for MuRT-PCR assay. The hybridization probe specific for the VARV sequence contained FAM/BHQ1 as a dye/quencher pair; MPXV-specific, TAMRA/BHQ2; CPXV-specific, JOE/BHQ1; VACV-specific, Cy5/BHQ3. The specificity and sensitivity of the developed method were assessed by analyzing DNA of 29 strains belonging to six orthopoxvirus species as well as the DNA samples isolated from archive clinical specimens of human smallpox cases and experimental specimens isolated from CPXV-infected mice and MPXV-infected marmot.