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Kojabad AA, Farzanehpour M, Galeh HEG, Dorostkar R, Jafarpour A, Bolandian M, Nodooshan MM. Droplet digital PCR of viral DNA/RNA, current progress, challenges, and future perspectives. J Med Virol 2021; 93:4182-4197. [PMID: 33538349 PMCID: PMC8013307 DOI: 10.1002/jmv.26846] [Citation(s) in RCA: 96] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 02/01/2021] [Indexed: 12/18/2022]
Abstract
High-throughput droplet-based digital PCR (ddPCR) is a refinement of the conventional polymerase chain reaction (PCR) methods. In ddPCR, DNA/RNA is encapsulated stochastically inside the microdroplets as reaction chambers. A small percentage of the reaction chamber contains one or fewer copies of the DNA or RNA. After PCR amplification, concentrations are determined based on the proportion of nonfluorescent partitions through the Poisson distribution. Some of the main features of ddPCR include high sensitivity and specificity, absolute quantification without a standard curve, high reproducibility, good tolerance to PCR inhibitor, and high efficacy compared to conventional molecular methods. These advantages make ddPCR a valuable addition to the virologist's toolbox. The following review outlines the recent technological advances in ddPCR methods and their applications in viral identification.
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Affiliation(s)
- Amir Asri Kojabad
- Applied Virology Research CenterBaqiyatallah University of Medical SciencesTehranIran
| | - Mahdieh Farzanehpour
- Applied Virology Research CenterBaqiyatallah University of Medical SciencesTehranIran
| | | | - Ruhollah Dorostkar
- Applied Virology Research CenterBaqiyatallah University of Medical SciencesTehranIran
| | - Ali Jafarpour
- Research Center for Clinical VirologyTehran University of Medical SciencesTehranIran
| | - Masoumeh Bolandian
- Applied Virology Research CenterBaqiyatallah University of Medical SciencesTehranIran
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Lei S, Chen S, Zhong Q. Digital PCR for accurate quantification of pathogens: Principles, applications, challenges and future prospects. Int J Biol Macromol 2021; 184:750-759. [PMID: 34171259 DOI: 10.1016/j.ijbiomac.2021.06.132] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 06/16/2021] [Accepted: 06/18/2021] [Indexed: 12/25/2022]
Abstract
Pathogens pose a severe threat to food safety and human health. The traditional methods for pathogen detection can't meet the growing diagnosis and control need. Digital PCR (dPCR) attracts a considerable attention for its ability to absolutely quantify pathogens with features of high selectivity, simplicity, accuracy and rapidity. The dPCR technique that achieves absolute quantification based on end-point measurement without standard curve offers a guideline for further genetic analysis and molecular diagnosis. It could contribute to the quantification of low level of nucleic acid, early detection and timely prevention of pathogenic diseases. In this review, 1442 publications about dPCR were selected and the detections of various pathogens by dPCR were reviewed comprehensively, including viruses, bacteria, parasites and fungi. A number of examples are cited to illustrate that dPCR is a new powerful tool with desired accuracy, sensitivity, and reproducibility for quantification of different types of pathogens. Moreover, the benefits, challenges and future prospects of the dPCR were also highlighted in this review.
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Affiliation(s)
- Shuwen Lei
- Guangdong Provincial Key Laboratory of Food Quality and Safety, College of Food Science, South China Agricultural University, Guangzhou 510642, China; Guangdong Laboratory of Lingnan Modern Agriculture, South China Agricultural University, Guangzhou 510642, China
| | - Song Chen
- Guangdong Provincial Key Laboratory of Food Quality and Safety, College of Food Science, South China Agricultural University, Guangzhou 510642, China; Guangdong Laboratory of Lingnan Modern Agriculture, South China Agricultural University, Guangzhou 510642, China
| | - Qingping Zhong
- Guangdong Provincial Key Laboratory of Food Quality and Safety, College of Food Science, South China Agricultural University, Guangzhou 510642, China; Guangdong Laboratory of Lingnan Modern Agriculture, South China Agricultural University, Guangzhou 510642, China.
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Application of One-Step Reverse Transcription Droplet Digital PCR for Dengue Virus Detection and Quantification in Clinical Specimens. Diagnostics (Basel) 2021; 11:diagnostics11040639. [PMID: 33916081 PMCID: PMC8066273 DOI: 10.3390/diagnostics11040639] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 03/26/2021] [Accepted: 03/26/2021] [Indexed: 12/24/2022] Open
Abstract
Detection and quantification of viruses in laboratory and clinical samples are standard assays in dengue virus (DENV) studies. The quantitative reverse transcription polymerase chain reaction (qRT-PCR) is considered to be the standard for DENV detection and quantification due to its high sensitivity. However, qRT-PCR offers only quantification relative to a standard curve and consists of several "in-house" components resulting in interlaboratory variations. We developed and optimized a protocol for applying one-step RT-droplet digital PCR (RT-ddPCR) for DENV detection and quantification. The lower limit of detection (LLOD95) and the lower limit of quantification (LLOQ) for RT-ddPCR were estimated to be 1.851 log10-copies/reaction and 2.337 log10-copies/reaction, respectively. The sensitivity of RT-ddPCR was found to be superior to qRT-PCR (94.87% vs. 90.38%, p = 0.039) while no false positives were detected. Quantification of DENV in clinical samples was independently performed in three laboratories showing interlaboratory variations with biases <0.5 log10-copies/mL. The RT-ddPCR protocol presented here could help harmonize DENV quantification results and improve findings in the field such as identifying a DENV titer threshold correlating with disease severity.
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Falak S, Macdonald R, Busby EJ, O'Sullivan DM, Milavec M, Plauth A, Kammel M, Zeichhardt H, Grunert HP, Kummrow A, Huggett JF. An assessment of the reproducibility of reverse transcription digital PCR quantification of HIV-1. Methods 2021; 201:34-40. [PMID: 33722693 DOI: 10.1016/j.ymeth.2021.03.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/28/2021] [Accepted: 03/08/2021] [Indexed: 11/30/2022] Open
Abstract
Viral load monitoring in human immunodeficiency virus type 1 (HIV-1) infection is often performed using reverse transcription quantitative PCR (RT-qPCR) to observe response to treatment and identify the development of resistance. Traceability is achieved using a calibration hierarchy traceable to the International Unit (IU). IU values are determined using consensus agreement derived from estimations by different laboratories. Such a consensus approach is necessary due to the fact that there are currently no reference measurement procedures available that can independently assign a reference value to viral reference materials for molecular in vitro diagnostic tests. Digital PCR (dPCR) is a technique that has the potential to be used for this purpose. In this paper, we investigate the ability of reverse transcriptase dPCR (RT-dPCR) to quantify HIV-1 genomic RNA without calibration. Criteria investigated included the performance of HIV-1 RNA extraction steps, choice of reverse transcription approach and selection of target gene with assays performed in both single and duplex format. We developed a protocol which was subsequently applied by two independent laboratories as part of an external quality assurance (EQA) scheme for HIV-1 genome detection. Our findings suggest that RT-dPCR could be used as reference measurement procedure to aid the value assignment of HIV-1 reference materials to support routine calibration of HIV-1 viral load testing by RT-qPCR.
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Affiliation(s)
- Samreen Falak
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany.
| | - Rainer Macdonald
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany
| | - Eloise J Busby
- National Measurement Laboratory, LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom
| | - Denise M O'Sullivan
- National Measurement Laboratory, LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom
| | - Mojca Milavec
- Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia
| | - Annabell Plauth
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany
| | - Martin Kammel
- INSTAND, Gesellschaft zur Foerderung der Qualitaetssicherung in medizinischen Laboratorien e.V., Ubierstr.20, D-40223 Düsseldorf, Germany; IQVD GmbH, Institut fuer Qualitaetssicherung in der Virusdiagnostik, Potsdamer Chaussee 80, 14129 Berlin, Germany
| | - Heinz Zeichhardt
- INSTAND, Gesellschaft zur Foerderung der Qualitaetssicherung in medizinischen Laboratorien e.V., Ubierstr.20, D-40223 Düsseldorf, Germany; IQVD GmbH, Institut fuer Qualitaetssicherung in der Virusdiagnostik, Potsdamer Chaussee 80, 14129 Berlin, Germany
| | - Hans-Peter Grunert
- GBD Gesellschaft fuer Biotechnologische Diagnostik mbH, Berlin, Potsdamer Chaussee 80, 14129 Berlin, Germany
| | - Andreas Kummrow
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany
| | - Jim F Huggett
- National Measurement Laboratory, LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom; School of Biosciences & Medicine, Faculty of Health & Medical Science, University of Surrey, Guildford GU2 7XH, United Kingdom.
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