Real-time fluorescent quantitative PCR非特异性扩增的研究进展

Real-time fluorescent quantitative PCR(RT-qPCR)因其高效快速、操作简便、高度敏感等优点获得广泛应用,但因其强大的放大功能而容易出现非特异性扩增的问题,尤其是荧光染料法中更加明显。文章对RT-qPCR的原理、非特异性扩增的发生因素、解决方案及该技术的应用前景进行了综述。

Application of Real-time Fluorescent Quantitative PCR in Plant

Real-time fluorescent quantitative PCR （RQ-PCR） is a detection method by adding fluorescent dye or fluorescent probe into the PCR reaction system, using fluorescent signal accumulation to monitor amplification reactions of PCR reaction process, and finally the unknown template can be quantitatively analyzed through the standard curve. So the detection level of PCR has improved from the qualitative to the quantitative. In order to provide a theoretical reference for further application, the principle, classification, advantages and disadvantages of RQ-PCR were intro- duced, and its application and progress in plants in recent years were reviewed.

Detection of Lactobacillus acidophilus in Fermented Material by Real-time Fluorescent Quantitative PCR

The species distinctive PCR primer of Lactobacillus acidophilus （ L. acidophilus） was designed according to 16S rRNA gene sequences of conunon Lac- tobacillus species in fermented material. Bacterial genome DNA of separated L. acidophilus in fermented sample was taken as template, and L. acidophilus in fer- mented material was conducted the quantitative determination by real-time quantitative PCR （RT-PCR）. Analysis on RT-PCR results shown that contents of L. aci- dophilus in the test sample reached 1.5 billion CFU / g. Test results shown that contents of L. acidophilus in fermented material could be detected accurately by the established RT-PCR method in the test. indicating that the established RT-PCR method could be aookued to the detection of L. acidophilus in fermented material.

Application of Real-time Fluorescent Quantitative PCR in Studies on Plants

Real-Lime fluorescent quantitative PCR is a method for quantitative analysis of gene expression developed in recent years, which has been widely used in various fields such as basic scientific research, clinical diagnosis, disease study, drug research and development since its appearance. It starts relatively late in study on plants, but has already been used for analysis of gene expression in plants and gene identification of exogenous genes. The principles or advantages and dis- advantages of real-time fluorescent quantitative PCR, or its potential problems and condition optimizations in tests were introduced in this study, and then the appli- cation and prospect of real-time fluorescent quantitative PCR in study on plants were also been discussed.

Development of Real-Time Fluorescent PCR for Rapid Detection of Haempohlius parasuis

[ Objective] To develop a real-time fluorescent PCR assay for rapid detection of Haempohlius parasuis （HPS）. [ Method] According to the conservative sequences of 16 S rRNA genes of HPS published in GenBank, a pair of specific primers was designed. The real-time fluorescent PCR was developed by optimizing primer concentration and annealing temperature. And its specificity and reproducibility were evaluated. Ten HPS- suspected samples were detected by the developed method. [ Result] The lowest detection limit of the developed real-time fluorescent PCR was 50 copies/μl. This method had good reproducibility, and its coefficient of variation was lower than 2%. Only HPS rather than Streptococcus suis type 2, Staphylococcus aureus, E. coli DH5 alpha, and swine Salmonella typhi could be detected by the developed real-time fluorescent PCR. The HPS-pesitive samples detected by this method were also positive when they were detected by isolation of bacteria or conventional PCR. [ Conclusion] The developed real-time fluorescent PCR is rapid, sensitive, specific and highly reproducible; thus, it can be used for rapid detection of HPS.

Synchronously Detecting Allergenic Ingredients of Peanut and Sesame in Food by Real-time Fluorescent PCR

Peanut,sesame and other raw materials of food are allergens for special populations.In this study,specific primers and TaqMan probes labeled by different fluorescences were designed targeting Ara h 2 gene of peanut and Ses i 1 gene of sesame.After the optimization of reaction conditions,a real-time fluorescent PCR method was established for simultaneous detection of allergenic ingredients of peanut and sesame in food.Genomic DNA samples of peanut,sesame,rice,wheat,barley,soybean,celery,maize,potato,tomato,walnut,groundnut in shell,cashew nut,sunflower seed,almond,apple,pear and strawberry,pork,beef,mutton and fish were used as templates for PCR amplification with deionized water as negative control template.Results indicated that the established real-time fluorescent PCR method could specifically identify allergenic ingredients of peanut and sesame simultaneously.Sensitivity test showed that the minimum detection limit of this method was 0.01%.Therefore,the established real-time fluorescent PCR method is a specific,sensitive and effective assay for simultaneously detecting allergenic ingredients of peanut and sesame in food.

Establishment of a Real-time Fluorescent Quantitative PCR Assay for Detection of Genetically Modified Maize Line MON88017

In order to improve the standardized technical systems of quantitative analyses for genetically modified organisms （GMOs） and products, ensure bio-safety and reduce ecological risk in China, a real-time fluorescent quantitative PCR assay was established for detection of genetically modified maize line MON88017. The established method was evaluated based on the specificity, sensitivity, accuracy and measurement uncertainty. The results showed that the established method had strong specificity in detection of genetically modified maize line MON88017. 1.50% MON88017 sample was detected with 29 replica- tions. The average measured value （ 1. 541% ） was close to the actual value （ 1.50% ） and the relative deviation was 2.70%. The variation coefficient of the measured value was 0.110 g ; the recovery was 100.00% and the measurement uncertainty was 0. 096. The limit of detection for genetically modified maize line MON88017 with the established method was 5 copies at the 97.5% confidence level. Thus, the real-time fluorescent quantitative PCR assay established in this study exhibited high specificity, accuracy and sensitivity, which could provide technical support for the safety supervision of genetically modified organ- isms and products in China.

Effects of Different Temperature and Time Durations of Virus Inactivation on Results of Real-time Fluorescence PCR Testing of COVID-19 Viruses

Summary:The novel coronavirus SARS-CoV-2 caused an outbreak of pneumonia in Wuhan,Hubei province of China in January 2020.This study aims to investigate the effects of different temperature and time durations of virus inactivation on the results of PCR testing for SARS-CoV-2.Twelve patients at the Renmin Hospital of Wuhan University suspected of being infected with SARS-CoV-2 were selected on February 13,2020 and throat swabs were taken.The swabs were stored at room tempcrature(20-25℃),then divided into aliquots and subjected to different temperature for different periods in order to inactivate the viruses(56℃for 30,45,60 min;65,70,80℃for 10,15,20 min).Control aliquots were stored at room temperature for 60 min.Then all aliquots were tested in a real-time fluorescence PCR using primers against SARS-CoV-2.Regardless of inactivation temperature and time,7 of 12 cases(58.3%)tested were positive for SARS-CoV-2 by PCR,and cycle threshold values were similar.These results suggest that virus inactivation parameters exert minimal infuence on PCR test results.Inactivation at 65℃for 10 min may be sufficient to ensure safe,reliable testing.

Detection of Ratoon Stunting Disease in Virus-free Seedcane via Real-time Fluorescence Quantitative PCR

This study was to develop the real-time fluorescence quantitative PCR technique for detecting the ratoon stunting disease （RSD） in virus-free seedcane seedlings. Healthy tissue culture seedlings were obtained from six plants of sugarcane ROC22, which had been confirmed RSD-positive by detecting the sugarcane juice, by employing the sugarcane seedlings production protocol. Real-time fluorescence quantitative PCR was used to detect RSD pathogens in tissue culture sam- pies. The results showed that target fragment of RSD pathogens was not found in all 10 samples in real-time fluorescence quantitative PCR, with the Ct values of 37 - 39. The healthy tissue culture sugarcane seedlings do not carry RSD pathogens, indicating that adopting healthy seedcane seedlings production technique could thoroughly get rid of RSD pathogens.

Development and Preliminary Application of SYBR Green I Real-Time Fluorescence Quantitative PCR Method for Detecting Porcine Parvovirus Virus

According to VP2 gene sequence of the porcine parvovirus virus strain NADL-2 （NC001718） available in GenBank （NC_001718）, a pair of specific primer was designed, and the target fragment of 431 bp was obtained by PCR amplification. The products were ligated with pMD18- T vector and then transformed into bacteria DH5α for recombinant plasmid extraction. After PCR identification and sequencing, recombinant plasmid was used as a standard template to establish the standard curve of SYBR Green I fluorescence quantitative PCR. Sensitivity test, specificity test and repeatability test were also determined. The results indicated that there was a good linear relationship between threshold cycle of the standard curve and template concentration, R2 =0.997 6. Tm ranged from 82.3 to 82.9 ℃, while the sensitivity was 72.1 copies/μl with good specificity and repeatability. The developed SYBR Green I real-time quantitative PCR method to detect PPV VP2 gene laid the basis for further studies on patho- oenesis, early clinical diaonosis of this virus and quantitative analysis of PPV infection.

Development of real-time PCR method for rapid detection and quantification of Heterosigma akashiwo

To rapidly detect the harmful algae H.akashiwo qualitatively and quantitatively, sequences of the 18S rDNA deduced from H.akashiwo were used for designing species-specific primers, and a RFQ-PCR (Real-time Fluorescent Quantitative Polymerase Chain Reaction) method was developed for quantitative detection of H.akashiwo. Primer H.akashiwo and TaqMan probe were designed, and the specificity of primer was checked with PCR. A calibration curve was constructed with cycle threshold value against visual counted cell number. And the value of the curve was tested with other H.akashiwo samples, which were assayed with both the RFQ-PCR method and visual count under microscope.

Primary application of a real-time quantitative polymerase chain reaction for the detection of human breast cancer related novel gene-Metadherin expression

Objective:The aim of this study was to detect the expression level of Metadherin (MTDH) in peripheral blood of the breast cancer patients by real-time fluorescence quantitative polymerase chain reaction (PCR),and to explore the relationship between expression of Metadherin gene in the patients peripheral blood and the clinic-pathological features in breast cancer. Methods:Real-time fluorescence quantitative polymerase chain reaction was employed to determine the expression level of Metadherin gene in 80 peripheral blood samples of breast cancer patients and healthy donors. Results:The expression of Metadherin gene in breast cancer patients peripheral blood were positive,in which 34 breast cancer patients were highly expressed,accounting for 55.7%,while the expression of Metadherin gene in normal females peripheral blood were negative,there was statistical significance (Ratio = 2.02±0.81,P < 0.05); Ratio of the Metadherin expression in breast cancer patients peripheral blood and the glyceraldehyde-3-phosphate dehydrogenase expression was 1.15 ± 0.36. REST software analysis showed that the expression of Metadherin gene was significantly up-regulated in breast cancer. Conclusion:The SYBR Green I quantitative real-time polymerase chain reaction method can successfully detect the expression level of Metadherin gene. Expression level of Metadherin gene in breast cancer patients peripheral blood is closely related to survival,and it maybe involved in the development of breast cancer and used as an indicator of prognosis.

小通量PCR仪光学扩增模拟器研制及应用

小通量PCR仪主要用于适应不同应用场景,应对各类应急检测、突发检测等需求,通常采用底部荧光或底侧部荧光采集的检测方式。本文结合其工作原理,区别于常规PCR仪的通量和反应孔分布设计,研制了一款集成温度光学校准功能,可组合使用、小巧便携的光学扩增模拟器,并通过实验验证了该装置的可靠性。

荧光定量PCR仪的边缘效应与实验误差分析

目的:探讨荧光定量PCR分析仪边缘效应及实验误差的原因。方法:通过比较部分国外知名品牌荧光定量PCR仪的光路系统及加热模块设计原理,分析边缘效应及实验误差产生的原因。结果:传统荧光定量PCR仪光路设计缺陷和加热模块的孔间温度均一性不足会导致边缘效应和实验误差,是影响荧光定量PCR结果重复性的重要原因。结论:了解不同品牌荧光定量PCR仪的检测原理,选购性能优良的荧光定量PCR仪,尽量避免实验误差,以保证实验结果的准确性。

聚合酶链式反应(PCR)荧光检测研究

本文研究了荧光能量传递技术 (fluorescenceresonanceenergytransfer,FRET) ,建立了一套基于该理论在聚合酶链式反应 (PCR)中用于荧光检测和溯源性研究的实验装置 。

2种荧光定量PCR扩增仪检测结果的比较

目的:观察2种荧光定量PCR扩增仪测定乙肝病毒定量(HBV DNA)的结果是否一致。方法:用2台PCR扩增仪同时对20份标本进行检测,观察2台荧光定量PCR定量扩增仪对HBV DNA测定结果的差异。结果:对20份标本HBV DNA含量的对数值进行相关性分析,二者相关性良好(r=0.96)。结论:通过2种荧光定量PCR扩增仪对20份随机样本的检测结果比较,2种仪器检测结果具有较好的一致性,可用于同时检测HBV DNA。

实验室认可中两台荧光定量PCR仪的比对性研究

目的对ABI-7300荧光定量PCR仪和上海宏石SLAN96P荧光定量PCR仪进行比对和偏差分析。方法在本院检验科ISO15189实验室认可中使用ABI7300和宏石SLAN96P荧光定量PCR仪同时检测20例涵盖整个仪器线性的HBVDNA标本,以ABI-7300荧光定量PCR仪作为参比仪器,SLAN96P荧光定量PCR仪作为实验仪器,进行回归分析,计算偏倚%,评价其是否可接受。结果 ABI-7300荧光定量PCR仪与SLAN96P荧光定量PCR仪检测HBV-DNA的定量结果相对偏倚为6.9%,符合CNAS-CL36《医学实验室质量和能力认可准则在基因扩增检验领域的应用说明》明确要求即系统误差绝对值小于7.5%。结论 ABI-7300荧光定量PCR仪与SLAN96P荧光定量PCR仪检测的HBV-DNA结果具有可比性,可为临床提供可接受的检验结果。

恒温PCR双通道荧光读数仪的系统设计

针对传统PCR检测仪在检测速度和精度上存在的问题,文中设计了恒温PCR双通道荧光读数仪系统,系统采用实时荧光核酸恒温扩增检测技术(SAT),大幅提高了扩增反应时间。然而考虑到SAT技术仍无法避免假阴性,文中在此基础上提出了双通道的光学系统设计,在检测样品阴阳性的同时对阴性样品进行实时监控。结果表明,该系统最快可在30 min内完成检测,可有效指示假阴性现象的出现,并具有检测速度快、精确度高、且稳定性好等优点。

荧光定量PCR仪的选购

荧光定量PCR技术已成为临床分子检测的重要手段之一,其以敏感性、特异性而被越来越多的科研人员所看好,荧光定量PCR仪的性能与检测结果的准确性密切相关。现将PCR仪选购过程中需注意的几点问题做一简单介绍。

荧光定量PCR仪光学校准方法与结果分析

实时荧光定量PCR仪特异性更强,自动化程度更高,且有效地解决了PCR污染的问题,应用领域及应用量都不断增加。但其设计更为复杂,温度模块和光学系统设计同时影响其性能和实验准确性,为定量PCR仪校准带来了巨大挑战。采用生物试剂等方式对定量PCR仪荧光部分校准缺乏溯源性,无法分析误差来源,存在较大缺陷。本文在对定量PCR仪影响因素和校准现状分析的基础上,采用Cyclertest 3D optical定量PCR仪光学校准系统对ABI 7500 Fast Real-Time定量PCR仪的温场部分和荧光系统进行了检测并对检测结果进行了分析,结果表明对温度模块和光学系统共同进行检测并分析相关性能够更科学全面地评估定量PCR仪性能,满足定量PCR仪校准需求。