scholarly journals Increased sensitivity using real-time dPCR for detection of SARS-CoV-2

BioTechniques ◽  
2020 ◽  
Author(s):  
Kyra Duong ◽  
Jiajia Ou ◽  
Zhaoliang Li ◽  
Zhaoqing Lv ◽  
Hao Dong ◽  
...  
Keyword(s):  
Real Time ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Absolute Quantification ◽  
Linear Dynamic Range ◽  
End Point ◽  
Increased Sensitivity ◽  
Quantification Accuracy ◽  
Sensitivity Specificity ◽  
Real Time Qpcr

A real-time dPCR system was developed to improve the sensitivity, specificity and quantification accuracy of end point dPCR. We compared three technologies – real-time qPCR, end point dPCR and real-time dPCR – in the context of SARS-CoV-2. Some improvement in limit of detection was obtained with end point dPCR compared with real-time qPCR, and the limit of detection was further improved with the newly developed real-time dPCR technology through removal of false-positive signals. Real-time dPCR showed increased linear dynamic range compared with end point dPCR based on quantitation from amplification curves. Real-time dPCR can improve the performance of TaqMan assays beyond real-time qPCR and end point dPCR with better sensitivity and specificity, absolute quantification and a wider linear range of detection.

scholarly journals A Novel Approach to the Bioluminescent Detection of the SARS-CoV-2 ORF1ab Gene by Coupling Isothermal RNA Reverse Transcription Amplification with a Digital PCR Approach

2021 ◽  
Vol 22 (3) ◽  
pp. 1017
Author(s):  
Zhongjie Fei ◽  
Rongbin Wei ◽  
Chu Cheng ◽  
Pengfeng Xiao
Keyword(s):  
Real Time ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Digital Pcr ◽  
Absolute Quantification ◽  
Global Public Health ◽  
Reaction Volume ◽  
Novel Approach ◽  
Highly Sensitive ◽  
Target Rna

The COVID-19 pandemic caused by the SARS-CoV-2 virus, which first emerged in December 2019, represents an ongoing global public health emergency. Here, we developed an improved and highly sensitive approach to SARS-CoV-2 detection via coupling bioluminescence in real-time (BART) and reverse-transcriptase loop-mediated amplification (RT-LAMP) protocols (RT-LAMP-BART) and was also compatible with a digital LAMP system (Rainsuit), which did not allow for real-time quantification but did, nonetheless, facilitate absolute quantification with a comparable detection limit of 104 copies/mL. Through improving RNA availability in samples to ensure the target RNA present in reaction, we additionally developed a simulated digital RT-LAMP approach using this same principle to enlarge the overall reaction volume and to achieve real-time detection with a limit of detection of 10 copies/mL, and with further improvements in the overall dynamic range of this assay system being achieved through additional optimization.

Development of a real-time reverse transcription-PCR assay to detect and quantify group A rotavirus equine-like G3 strains

2021 ◽  
Author(s):  
Eric M. Katz ◽  
Mathew D. Esona ◽  
Rashi Gautam ◽  
Michael D. Bowen
Keyword(s):  
Viral Load ◽  
Real Time ◽  
Reverse Transcription ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Human Populations ◽  
Pcr Assay ◽  
Group A Rotavirus ◽  
Reverse Transcription Pcr ◽  
Group A

Since 2013, group A rotavirus strains characterized as novel DS-1-like inter-genogroup reassortant ‘equine-like G3’ strains have emerged and spread across five continents among human populations in at least 14 countries. Here we report a novel one-step TaqMan quantitative real-time reverse transcription-PCR assay developed to genotype and quantify the viral load for samples containing rotavirus equine-like G3 strains. Using a universal G forward primer and a newly designed reverse primer and TaqMan probe, we developed and validated an assay with a linear dynamic range of 2.3 × 10 9 – 227 copies per reaction and a limit of detection of 227 copies. The percent positive agreement, percent negative agreement, and precision of our assay were 100.00%, 99.63%, and 100.00%, respectively. This assay can simultaneously detect and quantify the viral load for samples containing DS-1-like inter-genogroup reassortant equine-like G3 strains with high sensitivity and specificity, faster turnaround time, and decreased cost and will be valuable for high-throughput screening of stool samples collected to monitor equine-like G3 strain prevalence and circulation among human populations throughout the world.

scholarly journals Development of Quantitative Real-Time PCR Assays for Detection and Quantification of Surrogate Biological Warfare Agents in Building Debris and Leachate

2007 ◽  
Vol 73 (20) ◽  
pp. 6557-6565 ◽  
Author(s):  
Pascal E. Saikaly ◽  
Morton A. Barlaz ◽  
Francis L. de los Reyes
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Genomic Dna ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Fate And Transport ◽  
Biological Warfare ◽  
Quantitative Real Time Pcr ◽  
Pcr Assays ◽  
Detection And Quantification

ABSTRACT Evaluation of the fate and transport of biological warfare (BW) agents in landfills requires the development of specific and sensitive detection assays. The objective of the current study was to develop and validate SYBR green quantitative real-time PCR (Q-PCR) assays for the specific detection and quantification of surrogate BW agents in synthetic building debris (SBD) and leachate. Bacillus atrophaeus (vegetative cells and spores) and Serratia marcescens were used as surrogates for Bacillus anthracis (anthrax) and Yersinia pestis (plague), respectively. The targets for SYBR green Q-PCR assays were the 16S-23S rRNA intergenic transcribed spacer (ITS) region and recA gene for B. atrophaeus and the gyrB, wzm, and recA genes for S. marcescens. All assays showed high specificity when tested against 5 ng of closely related Bacillus and Serratia nontarget DNA from 21 organisms. Several spore lysis methods that include a combination of one or more of freeze-thaw cycles, chemical lysis, hot detergent treatment, bead beat homogenization, and sonication were evaluated. All methods tested showed similar threshold cycle values. The limit of detection of the developed Q-PCR assays was determined using DNA extracted from a pure bacterial culture and DNA extracted from sterile water, leachate, and SBD samples spiked with increasing quantities of surrogates. The limit of detection for B. atrophaeus genomic DNA using the ITS and B. atrophaeus recA Q-PCR assays was 7.5 fg per PCR. The limits of detection of S. marcescens genomic DNA using the gyrB, wzm, and S. marcescens recA Q-PCR assays were 7.5 fg, 75 fg, and 7.5 fg per PCR, respectively. Quantification of B. atrophaeus vegetative cells and spores was linear (R 2 > 0.98) over a 7-log-unit dynamic range down to 101 B. atrophaeus cells or spores. Quantification of S. marcescens (R 2 > 0.98) was linear over a 6-log-unit dynamic range down to 102 S. marcescens cells. The developed Q-PCR assays are highly specific and sensitive and can be used for monitoring the fate and transport of the BW surrogates B. atrophaeus and S. marcescens in building debris and leachate.

Development of a LUX real-time PCR for the detection and quantification of human herpesvirus 7

2009 ◽  
Vol 55 (3) ◽  
pp. 319-325 ◽  
Author(s):  
Massimiliano Bergallo ◽  
Cristina Costa ◽  
Maria Elena Terlizzi ◽  
Francesca Sidoti ◽  
Samuela Margio ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Primary Infection ◽  
Latent Infection ◽  
Dynamic Range ◽  
Human Herpesvirus ◽  
Clinical Samples ◽  
House Light ◽  
Pcr Assay ◽  
Sensitivity Specificity

Human herpesvirus 7 is a highly seroprevalent β-herpesvirus that, following primary infection, remains latent in CD4+ T cells and determines a persistent rather than a latent infection in various tissues and organs, including the lung and skin. This paper describes the development of an in-house light upon extension real-time PCR assay for quantification of human herpesvirus 7 DNA in clinical samples. The efficiency, sensitivity, specificity, inter- and intra-assay variability, and dynamic range have been determined. Subsequently, the assay has been validated by evaluating the human herpesvirus 7 load in bronchoalveolar lavages and skin specimens, chosen as 2 persistency sites, from healthy and pathological individuals. The real-time PCR assay developed in this study could be a useful tool to detect and quantify human herpesvirus 7 DNA in different clinical specimens to elucidate its epidemiological and pathogenic roles.

Comparison of real-time polymerase chain reaction and end-point polymerase chain reaction for the analysis of gene expression in preimplantation embryos

2006 ◽  
Vol 18 (3) ◽  
pp. 365 ◽  
Author(s):  
Árpád Baji Gál ◽  
Joseph Wallace Carnwath ◽  
Andras Dinnyes ◽  
Doris Herrmann ◽  
Heiner Niemann ◽  
...  
Keyword(s):  
Gene Expression ◽  
Polymerase Chain Reaction ◽  
Real Time ◽  
Reverse Transcription ◽  
Dynamic Range ◽  
Chain Reaction ◽  
Real Time System ◽  
The Real ◽  
End Point ◽  
Polymerase Chain

The aim of the present study was to compare real-time polymerase chain reaction (PCR) and end-point PCR with respect to their suitability for the analysis of gene expression in samples in which the number of cells is limited; for example, in studies of preimplantation embryonic development and to determine the variability of the real-time reverse transcription–PCR assay. The sensitivity, dynamic range and precision of both PCR systems were compared using a single mouse liver cDNA standard. The real-time system was 100-fold more sensitive than the end-point system and had a dynamic range of more than four orders of magnitude. The linear range for end-point PCR extended for two orders of magnitude using a fixed end-point of 31 cycles. The percentage standard error of the mean based on 30 replicates was 0.14% of the threshold cycle (Ct) value for the real-time system and 6.8% for the end-point fluorescence intensity. The coefficients of variation (CV) for reverse transcription combined with real-time analysis and the complete gene expression protocol consisting of mRNA isolation, reverse transcription and real-time PCR analysis were 0.6% and 1.4% of the Ct values, respectively. The present paper details, for the first time, measurement of the biological variation of individual mammalian oocytes. The CV was 1.8% of the Ct value for expression analysis of six bovine oocytes. The results are discussed in relation to the analysis of gene expression in preimplantation embryo development.

scholarly journals Development of Plasmid Calibrators for Absolute Quantification of miRNAs by Using Real-Time qPCR

2012 ◽  
Vol 14 (4) ◽  
pp. 314-321 ◽  
Author(s):  
Christine Formisano-Tréziny ◽  
Marina de San Feliciano ◽  
Jean Gabert
Keyword(s):  
Real Time ◽  
Absolute Quantification ◽  
Real Time Qpcr

scholarly journals Analytical Performances of Human Immunodeficiency Virus Type 1 RNA-Based Amplix® Real-Time PCR Platform for HIV-1 RNA Quantification

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
Christian Diamant Mossoro-Kpinde ◽  
Ralph-Sydney Mboumba Bouassa ◽  
Mohammad-Ali Jenabian ◽  
Serge Tonen Wolyec ◽  
Leman Robin ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Central Africa ◽  
Sub Saharan Africa ◽  
Clinical Samples ◽  
Absolute Bias ◽  
Sub Saharan ◽  
Hiv 1

Objectives. We evaluated the performances of Amplix real-time PCR platform developed by Biosynex (Strasbourg, France), combining automated station extraction (Amplix station 16 Dx) and real-time PCR (Amplix NG), for quantifying plasma HIV-1 RNA by lyophilized HIV-1 RNA-based Amplix reagents targeting gag and LTR, using samples from HIV-1-infected adults from Central African Republic. Results. Amplix real-time PCR assay showed low limit of detection (28 copies/mL), across wide dynamic range (1.4–10 log copies/mL), 100% sensitivity and 99% specificity, high reproducibility, and accuracy with mean bias < 5%. The assay showed excellent correlations and concordance of 95.3% with the reference HIV-1 RNA load assay (Roche), with mean absolute bias of +0.097 log copies/mL by Bland-Altman analysis. The assay was able to detect and quantify the most prevalent HIV-1 subtype strains and the majority of non-B subtypes, CRFs of HIV-1 group M, and HIV-1 groups N and O circulating in Central Africa. The Amplix assay showed 100% sensitivity and 99.6% specificity to diagnose virological failure in clinical samples from antiretroviral drug-experienced patients. Conclusions. The HIV-1 RNA-based Amplix real-time PCR platform constitutes sensitive and reliable system for clinical monitoring of HIV-1 RNA load in HIV-1-infected children and adults, particularly adapted to intermediate laboratory facilities in sub-Saharan Africa.

scholarly journals Absolute quantification of cassava brown streak virus mRNA by real-time qPCR

2017 ◽  
Vol 245 ◽  
pp. 5-13 ◽  
Author(s):  
Rudolph R. Shirima ◽  
Daniel G. Maeda ◽  
Edward Kanju ◽  
Gloria Ceasar ◽  
Flora I. Tibazarwa ◽  
...  
Keyword(s):  
Real Time ◽  
Absolute Quantification ◽  
Streak Virus ◽  
Cassava Brown Streak Virus ◽  
Real Time Qpcr ◽  
Brown Streak

scholarly journals Quantitation of Cell-Free and Cell-Associated Kaposi's Sarcoma-Associated Herpesvirus DNA by Real-Time PCR

2000 ◽  
Vol 38 (5) ◽  
pp. 1992-1995 ◽  
Author(s):  
Irene E. White ◽  
Thomas B. Campbell
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Kaposi's Sarcoma ◽  
Dynamic Range ◽  
Human Herpesvirus ◽  
Kaposi’S Sarcoma ◽  
Linear Dynamic Range ◽  
Pcr Assay ◽  
Herpesvirus 8 ◽  
Linear Dynamic

A real-time PCR assay for quantitation of Kaposi's sarcoma-associated herpes virus (KSHV or human herpesvirus 8) DNA was evaluated. The linear dynamic range was 10 to 105 copies of KSHV DNA (r 2 > 0.99). The accuracy of DNA purification and quantitation was less than ±0.4 log10copies for samples that contained from 10 to 105 copies of KSHV DNA. Cell-associated KSHV DNA was quantitated over a range of infected cell frequencies from 0.1 to 10−5, and cell-free KSHV DNA in plasma was quantitated over a range of 100 to 106 copies/ml. Real-time PCR provides a convenient method for quantitation of cell-free and cell-associated KSHV DNA in laboratory and clinical specimens.

scholarly journals Probe-Based Multiplex Real-Time PCR as a Diagnostic Tool to Distinguish Distinct Fungal Symbionts Associated With Euwallacea kuroshio and Euwallacea whitfordiodendrus in California

Plant Disease ◽  
2020 ◽  
Vol 104 (1) ◽  
pp. 227-238 ◽  
Author(s):  
Joseph D. Carrillo ◽  
Joey S. Mayorquin ◽  
Jason E. Stajich ◽  
Akif Eskalen
Keyword(s):  
Real Time ◽  
Limit Of Detection ◽  
Absolute Quantification ◽  
Coefficient Of Determination ◽  
Fungal Isolation ◽  
Real Time Quantitative Pcr ◽  
Field Samples ◽  
Symbiotic Fungi ◽  
Fusarium Dieback ◽  
Platanus Racemosa

California has been invaded by two distinct Euwallacea spp. that vector unique plant pathogenic symbiotic fungi on multiple hosts and cause Fusarium dieback. The objective of this study was to develop multiplex real-time quantitative PCR assays using hydrolysis probes targeting the β-tubulin gene to detect, distinguish, and quantify fungi associated with the polyphagous shot hole borer (PSHB; Euwallacea whitfordiodendrus, Fusarium euwallaceae, Graphium euwallaceae, and Paracremonium pembeum) as well as the Kuroshio shot hole borer (KSHB; Euwallacea kuroshio, Fusarium kuroshium, and Graphium kuroshium) from various sample types. Absolute quantification reaction efficiencies ranged from 88.2 to 104.3%, with a coefficient of determination >0.992 and a limit of detection of 100 copies µl−1 for all targets across both assays. Qualitative detection using the real-time assays on artificially inoculated avocado shoot extracts showed more sensitivity compared with conventional fungal isolation from wood. All symbiotic fungi, except P. pembeum, from PSHB and KSHB female heads were detectable and quantified. Field samples from symptomatic Platanus racemosa, Populus spp., and Salix spp. across 17 of 26 city parks were positively identified as PSHB and KSHB through detection of their symbiotic fungi, and both were found occurring together on five trees from three different park locations. The molecular assays presented here can be utilized to accurately identify fungi associated with these invasive pests in California.

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