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.

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.

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.

炭疽杆菌双毒力因子荧光PCR检测方法的建立及应用

由炭疽杆菌(Bacillus anthracis)引起的炭疽(anthrax)是严重危害人类和家畜健康的重大传染病。为了提高出入境口岸对不明粉未快件样品的查验效率,防范通过包裹夹带生化武器,本研究使用TaqMan探针技术,建立了针对炭疽杆菌两种毒力质粒pOX1和pOX2的双重荧光PCR检测方法,并对该方法的特异性、灵敏性和稳定性进行了试验。结果显示:本研究建立的炭疽杆菌双重荧光PCR检测方法具有较强的特异性,只特异性检出炭疽杆菌pOX1和pOX2,而与金黄色葡萄球菌等19种对照病原菌均无交叉反应;灵敏度与单重荧光PCR方法相近,最低检测限可达10 copies/μL;稳定性好,反应体系低温保存2、4、6、8个月后,检测阳性质粒的Ct值和峰值相差不大。应用该方法检测600份猪牛羊组织样本,均未检出炭疽杆菌阳性核酸。本研究建立的双重荧光PCR检测方法为炭疽杆菌的快速检测提供了技术支撑。

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.

贝类中沙门氏菌、阪崎肠杆菌双重RT-PCR检测方法研究

旨在建立一种快速、高效、经济、实用的双重实时荧光PCR方法,能同时快速、灵敏、特异地检测贝类中沙门氏菌、阪崎肠杆菌的双重实时荧光PCR体系。本研究以水产品中贝类为目标,根据特定基因序列,设计特异性扩增引物和TaqMan荧光探针,通过优化反应体系和条件,每种引物探针体系均可以特异性检测目标致病菌类型。2套引物探针体系组合可同时检测沙门氏菌、阪崎肠杆菌。双重RT-PCR方法的最低检测限可低至0.002 ng或0.02 ng基因组/反应,变异系数均小于2%。利用建立的双重RT-PCR方法检测14份贝类产品样本,样品实测结果与国家标准方法的检测结果一致,符合率为100%。结果表明,本研究建立的双重RT-PCR方法具有特异性、敏感性高、重复性好等优点,为贝类产品中沙门氏菌、阪崎肠杆菌的快速检测提供了新的技术方法。

一种基于磁性纳米粒子PCR的高通量SNP分型方法

利用磁性纳米粒子PCR扩增(MNPs-PCR)和等位基因特异性双色荧光探针(Cy3,Cy5)杂交,建立了一种单核苷酸多态性(SNP)分型的新方法.应用该方法对9个样本MTHFR基因的C677T多态进行检测,野生和突变型样本正错配信号比大于9·0,杂合型正错配信号比接近1·0,分型结果经测序验证.此方法无须产物纯化、浓缩,扫描分型结果快速、直观,是一种操作简单、快速、高通量、高灵敏度的分型方法.

食品中副溶血性弧菌toxR和tdh基因双色荧光PCR检测方法的建立

目的建立对副溶血性弧菌(Vibrio parahaemolyticus)特异性检测toxR(跨膜转录激活蛋白)基因和tdh(热稳定性直接溶血素)毒力基因的Taqman探针双色荧光PCR检测方法。方法根据副溶血性弧菌toxR基因和tdh基因,分别设计引物和探针,建立Taqman探针双色荧光PCR扩增体系,进行特异性、灵敏度试验;对副溶血性弧菌分离菌株实施检测,了解其tdh基因和tdh基因分布情况。结果结果表明,副溶血性弧菌标准菌株和3株从食物中毒患者中分离获得的分离株均出现toxR基因和tdh扩增曲线,而溶藻弧菌、单增李斯特菌等31株弧菌属其他菌株和肠杆菌科的菌株未见扩增曲线。从食品中分离的37株副溶血性弧菌分离株均未携带tdh毒力基因。副溶血性弧菌检测灵敏度可达到3.6×102cfu/mL。结论该方法可用于同时检测食品中副溶血性弧菌的特异性和毒力基因。

双重荧光实时定量PCR法检测TNF-α mRNA表达水平

目的:建立单管检测肿瘤坏死因子-α(TNF-α)和内参GAPDH mRNA表达水平的双重荧光实时定量PCR方法。方法:脂多糖刺激小鼠巨噬细胞Ana-1后提取细胞RNA,经反转录合成c DNA,应用自行设计的不同荧光标记的TNF-α和GAPDH引物探针,经PCR扩增后,在FAM通道和CY5通道分别读取Ct值,同时应用基因测序技术对结果进行验证,并构建质粒标准品分析该方法的灵敏度和重复性。结果:双重荧光实时定量PCR法检测TNF-α的灵敏度达4×101拷贝/μL,检测线性范围可达6个数量级,批内和批间重复性好。结论:新方法消除了目的基因与内参的加样误差,节约成本,快速准确,适用于TNF-αmRNA的定量检测。

双重实时荧光RT-PCR法检测肠道病毒方法的建立及应用

目的建立检测肠道病毒(EV)和肠道病毒71型(EV71)的双重实时荧光RT-PCR法。方法设计特异性引物和探针,建立双重实时荧光RT-PCR反应体系,绘制标准曲线,对该方法的灵敏度、精密度等进行评价。收集109例临床手足口病患者粪便和咽拭子标本用该法进行检测,并与EV71商品化试剂盒检测结果进行比较。结果双重荧光PCR法建立的EV和EV71标准曲线相关系数(r)均为0.998;该法检测EV和EV71的灵敏度分别达到0.5TCID50/mL和0.05TCID50/mL;检测EV和EV71的批内精密度均小于3%,总精密度均小于或等于4%;对肠道病毒及其他人类非肠道病毒进行检测,显示了良好的特异性。109例临床样本用该法检测出84例EV病毒阳性样本,其中EV71阳性56例,EV71总阳性率为51.4%;与单重荧光PCR商品化试剂盒的检测结果完全一致(P=1.000)。结论建立的双重实时荧光RT-PCR法灵敏度高、稳定性好,对手足口病的早期高通量快速诊断具有重要意义。

双重TaqMan荧光定量PCR在β-地中海贫血产前诊断中的应用

目的建立基因点突变双重TaqMan荧光定量PCR方法,实现β-地中海贫血(β-地贫)高风险胎儿产前基因诊断快速、准确。方法以每反应管检测一个位点的突变和野生型基因序列,建立β-地贫基因点突变双重TaqMan荧光定量PCR体系,检测β-地贫高风险胎儿绒毛标本6例、羊水标本32例,根据荧光PCR阳性扩增结果结合两荧光通道的Ct值差异分析受检标本的基因型,同时以常规RDB检测为对照,分析与评价检测结果。结果 6例胎儿绒毛标本中,RDB检测无法判断结果 1例,经该方法检测为野合纯合子;RDB检测误诊为CD41-42合并CD26双重杂合子1例,经该方法检测为CD41-42杂合子。32例胎儿羊水标本中,RDB检测无法判断的标本1例,经该方法检测为CD41-42杂合子。该3例标本经重新采集胎儿羊水标本复查,验证了定量检测结果的准确性。结论β基因点突变双重TaqMan荧光PCR定量检测方法,可实现β-地贫高风险胎儿的快速准确产前基因诊断,操作简单快速,结果准确可靠,是较为理想的β-地贫产前诊断方法。

食源性动物组织中CSFV和PRRSV双重双色荧光定量RT-PCR检测方法的建立及应用

为建立同时检检测食源性动物组织中猪瘟病毒(CSFV)和猪蓝耳病病毒(PRRSV)的双色荧光定量RT-PCR方法。本研究根据SCFV和PRRSV基因序列设计特异性的引物和不同荧光标记的TaqMan荧光探针,通过优化反应的体系和扩增条件,建立了能够检测食源性动物组织中SCFV和PRRSV的双重双色荧光定量PCR的方法。其检测下限为1×102拷贝/μL,而且与其他一些猪病病毒无交叉反应,具有良好的特异性。该方法重复性和稳定性试验表明其组内和组间的变异系数最高分别为4.2和4.5。对比试验表明,该方法对CSFV和PRRSV检验的敏感性为常规RT-PCR方法的200倍;该方法的建立为食源性动物组织中CSFV和PRRSV提供了有效手段,该方法特异性和敏感性较好,能够应用于临床检测。