1
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Xiong XS, Zhang XD, Yan JW, Huang TT, Liu ZZ, Li ZK, Wang L, Li F. Identification of Mycobacterium tuberculosis Resistance to Common Antibiotics: An Overview of Current Methods and Techniques. Infect Drug Resist 2024; 17:1491-1506. [PMID: 38628245 PMCID: PMC11020249 DOI: 10.2147/idr.s457308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 03/26/2024] [Indexed: 04/19/2024] Open
Abstract
Multidrug-resistant tuberculosis (MDR-TB) is an essential cause of tuberculosis treatment failure and death of tuberculosis patients. The rapid and reliable profiling of Mycobacterium tuberculosis (MTB) drug resistance in the early stage is a critical research area for public health. Then, most traditional approaches for detecting MTB are time-consuming and costly, leading to the inappropriate therapeutic schedule resting on the ambiguous information of MTB drug resistance, increasing patient economic burden, morbidity, and mortality. Therefore, novel diagnosis methods are frequently required to meet the emerging challenges of MTB drug resistance distinguish. Considering the difficulty in treating MDR-TB, it is urgently required for the development of rapid and accurate methods in the identification of drug resistance profiles of MTB in clinical diagnosis. This review discussed recent advances in MTB drug resistance detection, focusing on developing emerging approaches and their applications in tangled clinical situations. In particular, a brief overview of antibiotic resistance to MTB was present, referred to as intrinsic bacterial resistance, consisting of cell wall barriers and efflux pumping action and acquired resistance caused by genetic mutations. Then, different drug susceptibility test (DST) methods were described, including phenotype DST, genotype DST and novel DST methods. The phenotype DST includes nitrate reductase assay, RocheTM solid ratio method, and liquid culture method and genotype DST includes fluorescent PCR, GeneXpert, PCR reverse dot hybridization, ddPCR, next-generation sequencing and gene chips. Then, novel DST methods were described, including metabolism testing, cell-free DNA probe, CRISPR assay, and spectral analysis technique. The limitations, challenges, and perspectives of different techniques for drug resistance are also discussed. These methods significantly improve the detection sensitivity and accuracy of multidrug-resistant tuberculosis (MRT) and can effectively curb the incidence of drug-resistant tuberculosis and accelerate the process of tuberculosis eradication.
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Affiliation(s)
- Xue-Song Xiong
- Department of Laboratory Medicine, The Affiliated Huai’an Hospital of Yangzhou University, Huai’an, Jiangsu Province, People’s Republic of China
- Department of Laboratory Medicine, The Fifth People’s Hospital of Huai’an, Huai’an, Jiangsu Province, People’s Republic of China
| | - Xue-Di Zhang
- Department of Laboratory Medicine, Xuzhou Infectious Diseases Hospital, Xuzhou, Jiangsu Province, People’s Republic of China
| | - Jia-Wei Yan
- Department of Laboratory Medicine, Xuzhou Infectious Diseases Hospital, Xuzhou, Jiangsu Province, People’s Republic of China
| | - Ting-Ting Huang
- Department of Laboratory Medicine, The Affiliated Huai’an Hospital of Yangzhou University, Huai’an, Jiangsu Province, People’s Republic of China
- Department of Laboratory Medicine, The Fifth People’s Hospital of Huai’an, Huai’an, Jiangsu Province, People’s Republic of China
| | - Zhan-Zhong Liu
- Department of Pharmacy, Xuzhou Infectious Diseases Hospital, Xuzhou, Jiangsu Province, People’s Republic of China
| | - Zheng-Kang Li
- Department of Laboratory Medicine, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong Province, People’s Republic of China
| | - Liang Wang
- Department of Laboratory Medicine, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong Province, People’s Republic of China
| | - Fen Li
- Department of Laboratory Medicine, The Affiliated Huai’an Hospital of Yangzhou University, Huai’an, Jiangsu Province, People’s Republic of China
- Department of Laboratory Medicine, The Fifth People’s Hospital of Huai’an, Huai’an, Jiangsu Province, People’s Republic of China
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2
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Cleveland MH, He HJ, Milavec M, Bae YK, Vallone PM, Huggett JF. Digital PCR for the characterization of reference materials. Mol Aspects Med 2024; 96:101256. [PMID: 38359699 DOI: 10.1016/j.mam.2024.101256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 01/31/2024] [Accepted: 02/07/2024] [Indexed: 02/17/2024]
Abstract
Well-characterized reference materials support harmonization and accuracy when conducting nucleic acid-based tests (such as qPCR); digital PCR (dPCR) can measure the absolute concentration of a specific nucleic acid sequence in a background of non-target sequences, making it ideal for the characterization of nucleic acid-based reference materials. National Metrology Institutes are increasingly using dPCR to characterize and certify their reference materials, as it offers several advantages over indirect methods, such as UV-spectroscopy. While dPCR is gaining widespread adoption, it requires optimization and has certain limitations and considerations that users should be aware of when characterizing reference materials. This review highlights the technical considerations of dPCR, as well as its role when developing and characterizing nucleic acid-based reference materials.
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Affiliation(s)
- Megan H Cleveland
- Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, 20899, USA.
| | - Hua-Jun He
- Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, 20899, USA
| | - Mojca Milavec
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna Pot 111, 1000, Ljubljana, Slovenia
| | - Young-Kyung Bae
- Korea Research Institute of Standards and Science (KRISS), Daejeon, Republic of Korea
| | - Peter M Vallone
- Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, 20899, USA
| | - Jim F Huggett
- National Measurement Laboratory (NML), LGC, Queens Road, Teddington, TW11 0LY, Middlesex, UK; School of Biosciences & Medicine, Faculty of Health & Medical Science, University of Surrey, Guildford, UK
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3
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Yasuura M, Tan ZL, Horiguchi Y, Ashiba H, Fukuda T. Improvement of Sensitivity and Speed of Virus Sensing Technologies Using nm- and μm-Scale Components. SENSORS (BASEL, SWITZERLAND) 2023; 23:6830. [PMID: 37571612 PMCID: PMC10422600 DOI: 10.3390/s23156830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/20/2023] [Accepted: 07/27/2023] [Indexed: 08/13/2023]
Abstract
Various viral diseases can be widespread and cause severe disruption to global society. Highly sensitive virus detection methods are needed to take effective measures to prevent the spread of viral infection. This required the development of rapid virus detection technology to detect viruses at low concentrations, even in the biological fluid of patients in the early stages of the disease or environmental samples. This review describes an overview of various virus detection technologies and then refers to typical technologies such as beads-based assay, digital assay, and pore-based sensing, which are the three modern approaches to improve the performance of viral sensing in terms of speed and sensitivity.
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Affiliation(s)
- Masato Yasuura
- Sensing System Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba 305-8565, Ibaraki, Japan; (Z.L.T.); (Y.H.); (H.A.); (T.F.)
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4
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Bogožalec Košir A, Lužnik D, Tomič V, Milavec M. Evaluation of DNA Extraction Methods for Reliable Quantification of Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa. BIOSENSORS 2023; 13:bios13040463. [PMID: 37185538 PMCID: PMC10136035 DOI: 10.3390/bios13040463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/25/2023] [Accepted: 04/04/2023] [Indexed: 05/17/2023]
Abstract
Detection and quantification of DNA biomarkers relies heavily on the yield and quality of DNA obtained by extraction from different matrices. Although a large number of studies have compared the yields of different extraction methods, the repeatability and intermediate precision of these methods have been largely overlooked. In the present study, five extraction methods were evaluated, using digital PCR, to determine their efficiency in extracting DNA from three different Gram-negative bacteria in sputum samples. The performance of two automated methods (GXT NA and QuickPick genomic DNA extraction kit, using Arrow and KingFisher Duo automated systems, respectively), two manual kit-based methods (QIAamp DNA mini kit; DNeasy UltraClean microbial kit), and one manual non-kit method (CTAB), was assessed. While GXT NA extraction kit and the CTAB method have the highest DNA yield, they did not meet the strict criteria for repeatability, intermediate precision, and measurement uncertainty for all three studied bacteria. However, due to limited clinical samples, a compromise is necessary, and the GXT NA extraction kit was found to be the method of choice. The study also showed that dPCR allowed for accurate determination of extraction method repeatability, which can help standardize molecular diagnostic approaches. Additionally, the determination of absolute copy numbers facilitated the calculation of measurement uncertainty, which was found to be influenced by the DNA extraction method used.
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Affiliation(s)
- Alexandra Bogožalec Košir
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna Pot 111, 1000 Ljubljana, Slovenia
| | - Dane Lužnik
- University Clinic of Respiratory and Allergic Diseases Golnik, Golnik 36, 4204 Golnik, Slovenia
| | - Viktorija Tomič
- University Clinic of Respiratory and Allergic Diseases Golnik, Golnik 36, 4204 Golnik, Slovenia
| | - Mojca Milavec
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna Pot 111, 1000 Ljubljana, Slovenia
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5
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Hou Y, Chen S, Zheng Y, Zheng X, Lin JM. Droplet-based digital PCR (ddPCR) and its applications. Trends Analyt Chem 2022. [DOI: 10.1016/j.trac.2022.116897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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6
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Ma D, Straathof J, Liu Y, Hull NM. Monitoring SARS-CoV-2 RNA in Wastewater with RT-qPCR and Chip-Based RT-dPCR: Sewershed-Level Trends and Relationships to COVID-19. ACS ES&T WATER 2022; 2:2084-2093. [PMID: 37552751 PMCID: PMC9173673 DOI: 10.1021/acsestwater.2c00055] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 05/10/2022] [Accepted: 05/11/2022] [Indexed: 08/10/2023]
Abstract
We evaluated the performance of reverse transcription quantitative PCR (uniplex and duplex RT-qPCR) and chip-based digital PCR (duplex RT-dPCR) using CDC N1 and CDC N2 assays for longitudinal monitoring of SARS-CoV-2 RNA in influent wastewater samples (n = 281) from three wastewater plants in Ohio from January 2021 to January 2022. Human fecal virus (PMMoV) and wastewater flow rate were used to normalize SARS-CoV-2 concentrations. SARS-CoV-2 measurements and COVID-19 cases were strongly correlated, but normalization effects on correlations varied between sewersheds. SARS-CoV-2 measurements by RT-qPCR were strongly correlated with 7-day moving average COVID-19 cases (average Spearman's ρ = 0.58, p < 0.05). SARS-CoV-2 was detected more frequently in samples with duplex RT-dPCR than with duplex RT-qPCR during periods of low COVID-19 cases. Duplex and uniplex RT-qPCR N1 concentrations were more strongly correlated with cases (ρ = 0.62) than N2 (ρ = 0.52). RT-dPCR correlations (average ρ = 0.21) were weaker than those of RT-qPCR (average ρ = 0.58). We also share practical experience from establishing wastewater surveillance. Per sample, RT-qPCR had a lower cost ($6 vs $18) and sample turnaround time (3-4 h vs 7-9 h) than RT-dPCR. These findings reinforce selection and use of PCR-based wastewater surveillance tools.
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Affiliation(s)
- Daniel Ma
- Department of Civil, Environmental and Geodetic
Engineering, The Ohio State University, Columbus, Ohio 43210,
United States
| | - Judith Straathof
- Department of Civil, Environmental and Geodetic
Engineering, The Ohio State University, Columbus, Ohio 43210,
United States
| | - Yijing Liu
- Department of Civil, Environmental and Geodetic
Engineering, The Ohio State University, Columbus, Ohio 43210,
United States
| | - Natalie Marie Hull
- Department of Civil, Environmental and Geodetic
Engineering, The Ohio State University, Columbus, Ohio 43210,
United States
- The Sustainability Institute, The Ohio
State University, Columbus, Ohio 43210, United
States
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7
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Zhang Y, Zhao Y, Cole T, Zheng J, Bayinqiaoge, Guo J, Tang SY. Microfluidic flow cytometry for blood-based biomarker analysis. Analyst 2022; 147:2895-2917. [PMID: 35611964 DOI: 10.1039/d2an00283c] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Flow cytometry has proven its capability for rapid and quantitative analysis of individual cells and the separation of targeted biological samples from others. The emerging microfluidics technology makes it possible to develop portable microfluidic diagnostic devices for point-of-care testing (POCT) applications. Microfluidic flow cytometry (MFCM), where flow cytometry and microfluidics are combined to achieve similar or even superior functionalities on microfluidic chips, provides a powerful single-cell characterisation and sorting tool for various biological samples. In recent years, researchers have made great progress in the development of the MFCM including focusing, detecting, and sorting subsystems, and its unique capabilities have been demonstrated in various biological applications. Moreover, liquid biopsy using blood can provide various physiological and pathological information. Thus, biomarkers from blood are regarded as meaningful circulating transporters of signal molecules or particles and have great potential to be used as non (or minimally)-invasive diagnostic tools. In this review, we summarise the recent progress of the key subsystems for MFCM and its achievements in blood-based biomarker analysis. Finally, foresight is offered to highlight the research challenges faced by MFCM in expanding into blood-based POCT applications, potentially yielding commercialisation opportunities.
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Affiliation(s)
- Yuxin Zhang
- Department of Electronic, Electrical and Systems Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
| | - Ying Zhao
- National Chengdu Centre of Safety Evaluation of Drugs, West China Hospital of Sichuan University, Chengdu, China
| | - Tim Cole
- Department of Electronic, Electrical and Systems Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
| | - Jiahao Zheng
- Department of Electronic, Electrical and Systems Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
| | - Bayinqiaoge
- Department of Electronic, Electrical and Systems Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
| | - Jinhong Guo
- The M.O.E. Key Laboratory of Laboratory Medical Diagnostics, The College of Laboratory Medicine, Chongqing Medical University, #1 Yixueyuan Road, Yuzhong District, Chongqing, 400016, China.
| | - Shi-Yang Tang
- Department of Electronic, Electrical and Systems Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
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8
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Abstract
Microfluidics has enabled a new era of cellular and molecular assays due to the small length scales, parallelization, and the modularity of various analysis and actuation functions. Droplet microfluidics, in particular, has been instrumental in providing new tools for biology with its ability to quickly and reproducibly generate drops that act as individual reactors. A notable beneficiary of this technology has been single-cell RNA sequencing, which has revealed new heterogeneities and interactions for the fundamental unit of life. However, viruses far surpass the diversity of cellular life, affect the dynamics of all ecosystems, and are a chronic source of global health crises. Despite their impact on the world, high-throughput and high-resolution viral profiling has been difficult, with conventional methods being limited to population-level averaging, large sample volumes, and few cultivable hosts. Consequently, most viruses have not been identified and studied. Droplet microfluidics holds the potential to address many of these limitations and offers new levels of sensitivity and throughput for virology. This Feature highlights recent efforts that have applied droplet microfluidics to the detection and study of viruses, including for diagnostics, virus-host interactions, and cell-independent virus assays. In combination with traditional virology methods, droplet microfluidics should prove a potent tool toward achieving a better understanding of the most abundant biological species on Earth.
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Affiliation(s)
- Wenyang Jing
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Hee-Sun Han
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 West Gregory Drive, Urbana, Illinois 61801, United States
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9
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Tan LL, Loganathan N, Agarwalla S, Yang C, Yuan W, Zeng J, Wu R, Wang W, Duraiswamy S. Current commercial dPCR platforms: technology and market review. Crit Rev Biotechnol 2022; 43:433-464. [PMID: 35291902 DOI: 10.1080/07388551.2022.2037503] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Digital polymerase chain reaction (dPCR) technology has provided a new technique for molecular diagnostics, with superior advantages, such as higher sensitivity, precision, and specificity over quantitative real-time PCRs (qPCR). Eight companies have offered commercial dPCR instruments: Fluidigm Corporation, Bio-Rad, RainDance Technologies, Life Technologies, Qiagen, JN MedSys Clarity, Optolane, and Stilla Technologies Naica. This paper discusses the working principle of each offered dPCR device and compares the associated: technical aspects, usability, costs, and current applications of each dPCR device. Lastly, up-and-coming dPCR technologies are also presented, as anticipation of how the dPCR device landscape may likely morph in the next few years.
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Affiliation(s)
- Li Ling Tan
- Singapore Institute of Manufacturing Technology, Singapore, Singapore.,Materials Science and Engineering School, Nanyang Technological University, Singapore, Singapore
| | - Nitin Loganathan
- Singapore Institute of Manufacturing Technology, Singapore, Singapore
| | - Sushama Agarwalla
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Hyderabad, India
| | - Chun Yang
- Mechanical and Aerospace Engineering School, Nanyang Technological University, Singapore, Singapore
| | - Weiyong Yuan
- Faculty of Materials & Energy, Institute for Clean Energy and Advanced Materials, Southwest University, Chongqing, China.,Chongqing Key Laboratory for Advanced Materials and Technologies of Clean Energies, Chongqing, China
| | - Jasmine Zeng
- Singapore Institute of Manufacturing Technology, Singapore, Singapore
| | - Ruige Wu
- Singapore Institute of Manufacturing Technology, Singapore, Singapore
| | - Wei Wang
- Singapore Institute of Manufacturing Technology, Singapore, Singapore
| | - Suhanya Duraiswamy
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Hyderabad, India
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10
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Milavec M, Cleveland MH, Bae YK, Wielgosz RI, Vonsky M, Huggett JF. Metrological framework to support accurate, reliable, and reproducible nucleic acid measurements. Anal Bioanal Chem 2021; 414:791-806. [PMID: 34738220 PMCID: PMC8568362 DOI: 10.1007/s00216-021-03712-x] [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: 07/04/2021] [Revised: 09/05/2021] [Accepted: 10/01/2021] [Indexed: 11/29/2022]
Abstract
Nucleic acid analysis is used in many areas of life sciences such as medicine, food safety, and environmental monitoring. Accurate, reliable measurements of nucleic acids are crucial for maximum impact, yet users are often unaware of the global metrological infrastructure that exists to support these measurements. In this work, we describe international efforts to improve nucleic acid analysis, with a focus on the Nucleic Acid Analysis Working Group (NAWG) of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM). The NAWG is an international group dedicated to improving the global comparability of nucleic acid measurements; its primary focus is to support the development and maintenance of measurement capabilities and the dissemination of measurement services from its members: the National Metrology Institutes (NMIs) and Designated Institutes (DIs). These NMIs and DIs provide DNA and RNA measurement services developed in response to the needs of their stakeholders. The NAWG members have conducted cutting edge work over the last 20 years, demonstrating the ability to support the reliability, comparability, and traceability of nucleic acid measurement results in a variety of sectors.
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Affiliation(s)
- Mojca Milavec
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna pot 111, 1000, Ljubljana, Slovenia.
| | - Megan H Cleveland
- National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD, 20899, USA
| | - Young-Kyung Bae
- Korea Research Institute of Standards and Science (KRISS), Daejeon, Republic of Korea
| | - Robert I Wielgosz
- Bureau International Des Poids Et Mesures (BIPM), Pavillon de Breteuil, 92312, Sèvres Cedex, France
| | - Maxim Vonsky
- D.I. Mendeleev Institute for Metrology, Moskovsky pr., 19, Saint-Petersburg, 190005, Russian Federation
| | - Jim F Huggett
- National Measurement Laboratory (NML), LGC, Queens Road, Teddington, TW11 0LY, Middlesex, UK.,School of Biosciences & Medicine, Faculty of Health & Medical Science, University of Surrey, Guildford, UK
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11
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Sun C, Liu L, Vasudevan HN, Chang KC, Abate AR. Accurate Bulk Quantitation of Droplet Digital Polymerase Chain Reaction. Anal Chem 2021; 93:9974-9979. [PMID: 34252272 PMCID: PMC8829825 DOI: 10.1021/acs.analchem.1c00877] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Droplet digital PCR
provides superior accuracy for nucleic acid
quantitation. The requirement of microfluidics to generate and analyze
the emulsions, however, is a barrier to its adoption, particularly
in low resource settings or clinical laboratories. Here, we report
a novel method to prepare ddPCR droplets by vortexing and readout
of the results by bulk analysis of recovered amplicons. We demonstrate
the approach by accurately quantitating SARS-CoV-2 sequences using
entirely bulk processing and no microfluidics. Our approach for quantitating
reactions should extend to all digital assays that generate amplicons,
including digital PCR and LAMP conducted in droplets, microchambers,
or nanoliter wells. More broadly, our approach combines important
attributes of ddPCR, including enhanced accuracy and robustness to
inhibition, with the high-volume sample processing ability of quantitative
PCR.
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Affiliation(s)
- Chen Sun
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California 94158, United States
| | - Leqian Liu
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California 94158, United States
| | - Harish N Vasudevan
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California 94158, United States.,Department of Radiation Oncology, University of California San Francisco, San Francisco, California 94158, United States
| | - Kai-Chun Chang
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California 94158, United States
| | - Adam R Abate
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California 94158, United States.,California Institute for Quantitative Biosciences, University of California San Francisco, San Francisco, California 94158, United States.,Chan Zuckerberg Biohub, San Francisco, California 94158, United States
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12
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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: 105] [Impact Index Per Article: 35.0] [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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13
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Milavec M, Pavšič J, Bogožalec Košir A, Jones GM, O'Sullivan DM, Devonshire AS, Van Heuverswyn F, Karczmarczyk M, Neeb J, Plauth A, Corbisier P, Schimmel H, Kummrow A, Neukammer J, Foy CA, Kammel M, Grunert HP, Zeichhardt H, Huggett JF. The performance of human cytomegalovirus digital PCR reference measurement procedure in seven external quality assessment schemes over four years. Methods 2021; 201:65-73. [PMID: 33812016 DOI: 10.1016/j.ymeth.2021.03.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 03/18/2021] [Accepted: 03/22/2021] [Indexed: 11/16/2022] Open
Abstract
A candidate digital PCR (dPCR)-based reference measurement procedure for quantification of human cytomegalovirus (hCMV) was evaluated in 10 viral load comparison schemes (seven external quality assessment (EQA) and three additional training schemes) organized by INSTAND e.V. over four years (between September 2014 and March 2018). Four metrology institutes participated in these schemes using the same extraction method and dPCR measurement procedure for the hCMV specific target sequence of UL54 gene. The calibration independent reference measurement procedure results from the metrology institutes were compared to the results of the clinical diagnostic laboratories applying hCMV qPCR measurement procedures calibrated to reference materials. While the criteria for the acceptable deviation from the target value interval for INSTAND's EQA schemes is from -0.8 log10 to +0.8 log10, the majority of dPCR results were between -0.2 log10 to +0.2 log10. Only 4 out of 45 results exceeded this interval with the maximum deviation of -0.542 log10. In the training schemes containing samples with lower hCMV concentrations, more than half of the results deviated less than ±0.2 log10 from the target value, while more than 95% deviated less than ±0.4 log10 from the target value. Evaluation of intra- and inter-laboratory variation of dPCR results confirmed high reproducibility and trueness of the method. This work demonstrates that dPCR has the potential to act as a calibration independent reference measurement procedure for the value assignment of hCMV calibration and reference materials to support qPCR calibration as well as ultimately for routine hCMV load testing.
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Affiliation(s)
- Mojca Milavec
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia.
| | - Jernej Pavšič
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Alexandra Bogožalec Košir
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Gerwyn M Jones
- National Measurement Laboratory (NML), LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom
| | - Denise M O'Sullivan
- National Measurement Laboratory (NML), LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom
| | - Alison S Devonshire
- National Measurement Laboratory (NML), LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom
| | | | | | - Jannika Neeb
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, D-10587 Berlin, Germany
| | - Annabell Plauth
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, D-10587 Berlin, Germany
| | | | - Heinz Schimmel
- European Commission, Joint Research Centre (JRC), Geel, Belgium
| | - Andreas Kummrow
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, D-10587 Berlin, Germany
| | - Jörg Neukammer
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, D-10587 Berlin, Germany
| | - Carole A Foy
- National Measurement Laboratory (NML), LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom
| | - 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, D-14129 Berlin, Germany
| | - Hans-Peter Grunert
- GBD Gesellschaft fuer Biotechnologische Diagnostik mbH, Berlin, Potsdamer Chaussee 80, D-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, D-14129 Berlin, Germany; GBD Gesellschaft fuer Biotechnologische Diagnostik mbH, Berlin, Potsdamer Chaussee 80, D-14129 Berlin, Germany
| | - Jim F Huggett
- National Measurement Laboratory (NML), LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom; School of Biosciences & Medicine, Faculty of Health & Medical Science, University of Surrey, Guildford, United Kingdom
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14
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Comprehensive characterization and quantification of adeno associated vectors by size exclusion chromatography and multi angle light scattering. Sci Rep 2021; 11:3012. [PMID: 33542328 PMCID: PMC7862616 DOI: 10.1038/s41598-021-82599-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 01/22/2021] [Indexed: 01/10/2023] Open
Abstract
Adeno associated virus (AAV) capsids are a leading modality for in vivo gene delivery. Complete and precise characterization of capsid particles, including capsid and vector genome concentration, is necessary to safely and efficaciously dose patients. Size exclusion chromatography (SEC) coupled to multiangle light scattering (MALS) offers a straightforward approach to comprehensively characterize AAV capsids. The current study demonstrates that this method provides detailed AAV characterization information, including but not limited to aggregation profile, size-distribution, capsid content, capsid molar mass, encapsidated DNA molar mass, and total capsid and vector genome titer. Currently, multiple techniques are required to generate this information, with varying accuracy and precision. In the current study, a new series of equations for SEC-MALS are used in tandem with intrinsic properties of the capsids and encapsidated DNA to quantify multiple physical AAV attributes in one 20-min run with minimal sample manipulation, high accuracy, and high precision. These novel applications designate this well-established method as a powerful tool for product development and process analytics in future gene therapy programs.
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15
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Sun C, Liu L, Vasudevan HN, Chang KC, Abate AR. Accurate bulk quantitation of droplet digital PCR. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021:2021.01.13.424628. [PMID: 33469578 PMCID: PMC7814815 DOI: 10.1101/2021.01.13.424628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Droplet digital PCR provides superior accuracy in nucleic acid quantitation. The requirement of microfluidics to generate and analyze the emulsions, however, is a barrier to its adoption, particularly in low resource or clinical settings. Here, we report a novel method to prepare ddPCR droplets by vortexing and readout the results by bulk analysis of recovered amplicons. We demonstrate the approach by accurately quantitating SARS-CoV-2 sequences using entirely bulk processing and no microfluidics. Our approach for quantitating reactions should extend to all digital assays that generate amplicons, including digital PCR and LAMP conducted in droplets, microchambers, or nanoliter wells. More broadly, our approach combines important attributes of ddPCR, including enhanced accuracy and robustness to inhibition, with the high-volume sample processing ability of quantitative PCR.
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Affiliation(s)
- Chen Sun
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA 94158, USA
| | - Leqian Liu
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA 94158, USA
| | - Harish N. Vasudevan
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA 94158, USA
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA 94158, USA
| | - Kai-Chun Chang
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA 94158, USA
| | - Adam R. Abate
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA 94158, USA
- California Institute for Quantitative Biosciences, University of California San Francisco, San Francisco, CA 94158, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
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16
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Deiana M, Mori A, Piubelli C, Scarso S, Favarato M, Pomari E. Assessment of the direct quantitation of SARS-CoV-2 by droplet digital PCR. Sci Rep 2020; 10:18764. [PMID: 33127953 PMCID: PMC7599326 DOI: 10.1038/s41598-020-75958-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 10/20/2020] [Indexed: 01/08/2023] Open
Abstract
Droplet digital PCR (ddPCR) is a sensitive and reproducible technology widely used for quantitation of several viruses. The aim of this study was to evaluate the 2019-nCoV CDC ddPCR Triplex Probe Assay (BioRad) performance, comparing the direct quantitation of SARS-CoV-2 on nasopharyngeal swab with the procedure applied to the extracted RNA. Moreover, two widely used swab types were compared (UTM 3 mL and ESwab 1 mL, COPAN). A total of 50 nasopharyngeal swabs (n = 25 UTM 3 mL and n = 25 ESwab 1 mL) from SARS-CoV-2 patients, collected during the pandemic at IRCCS Sacro Cuore Don Calabria Hospital (Veneto Region, North-East Italy), were used for our purpose. After heat inactivation, an aliquot of swab medium was used for the direct quantitation. Then, we compared the direct method with the quantitation performed on the RNA purified from nasopharyngeal swab by automated extraction. We observed that the direct approach achieved generally equal RNA copies compared to the extracted RNA. The results with the direct quantitation were more accurate on ESwab with a sensitivity of 93.33% [95% CI, 68.05 to 99.83] and specificity of 100.00% for both N1 and N2. On the other hand, on UTM we observed a higher rate of discordant results for N1 and N2. The human internal amplification control (RPP30) showed 100% of both sensitivity and specificity independent of swabs and approaches. In conclusion, we described a direct quantitation of SARS-CoV-2 in nasopharyngeal swab. Our approach resulted in an efficient quantitation, without automated RNA extraction and purification. However, special care needs to be taken on the potential bias due to the conservation of samples and to the heating treatment, as we used thawed and heat inactivated material. Further studies on a larger cohort of samples are warranted to evaluate the clinical value of this direct approach.
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Affiliation(s)
- Michela Deiana
- Department of Infectious-Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Via Don A. Sempreboni, 5 - 37024 Negrar di Valpolicella, Verona, VR, Italy
| | - Antonio Mori
- Department of Infectious-Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Via Don A. Sempreboni, 5 - 37024 Negrar di Valpolicella, Verona, VR, Italy
- Department of Diagnostics and Public Health, University of Verona, Verona, Italy
| | - Chiara Piubelli
- Department of Infectious-Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Via Don A. Sempreboni, 5 - 37024 Negrar di Valpolicella, Verona, VR, Italy
| | - Salvatore Scarso
- Department of Infectious-Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Via Don A. Sempreboni, 5 - 37024 Negrar di Valpolicella, Verona, VR, Italy
| | | | - Elena Pomari
- Department of Infectious-Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Via Don A. Sempreboni, 5 - 37024 Negrar di Valpolicella, Verona, VR, Italy.
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17
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Exclusive use of digital PCR allows an absolute assay of heat-killed Lactobacilli in foods targeting multiple copies of 16S rDNA. Sci Rep 2020; 10:12691. [PMID: 32728064 PMCID: PMC7391674 DOI: 10.1038/s41598-020-69206-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 07/09/2020] [Indexed: 11/15/2022] Open
Abstract
The real-time PCR (qPCR) and digital PCR (dPCR) to amplify a single-copy of house-keeping genes (i.e., hsp60, pheS or tuf) are used for the assay of limited microbial species. In general, with a single-copy gene, there are obviously varied DNA sequences for even the same microbial species, which could cause difficulties with design of primers and probes for PCR when targeting various single copy genes. In general, for identification by dPCR (as a representative case: Lactobacillus paracasei), accumulated DNA sequence information of 16S rDNA, which is much more frequently used, should be targeted. In contrast, next-generation sequencing revealed that there are five copies of 16S rDNA in a live L. paracasei MCC1849. Therefore, we aimed to reveal, if heat-killed L. paracasei supplemented in nutritional foods that aid the host immune system have the relevant five copies per chromosomal DNA, and if the relevant copies remain unchanged on the same chromosomal DNA or remain to be different chromosomal DNA fragments. So, we revealed the actual distribution of the potential original five copies of 16S rDNA using our innovative dPCR, in which both 16S rDNA and hsp60 genes were simultaneously elongated. The molecular ratios of 16S rDNA/hsp60 dispersed in the dPCR chip were then estimated. The 16S rDNA/hsp60 molecular ratios of the heat-killed L. paracasei in foods, resultantly ranged from 5.0 to 7.2, being the same or higher than that of the five copies determined by next-generation sequencing. The 16S rDNA copy number/ratio indicated the chromosomal DNA molecular number and the associated cell number. As significance, different nutritional foods could potentially cause the loss of chromosomal DNA of supplemented beneficial microbes to a much greater degree. Our absolute dPCR does not require standard correlative samples for the estimation of final products. The estimation principle of the ratio of 16S rDNA/a house-keeping single-copy gene by our absolute dPCR could lead to a useful and accurate assay for various nutritional foods.
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18
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Rocchigiani AM, Tilocca MG, Portanti O, Vodret B, Bechere R, Di Domenico M, Savini G, Lorusso A, Puggioni G. Development of a Digital RT-PCR Method for Absolute Quantification of Bluetongue Virus in Field Samples. Front Vet Sci 2020; 7:170. [PMID: 32373633 PMCID: PMC7186476 DOI: 10.3389/fvets.2020.00170] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 03/11/2020] [Indexed: 11/24/2022] Open
Abstract
Bluetongue (BT) is a major Office International des Epizooties (OIE)-listed disease of wild and domestic ruminants caused by several serotypes of Bluetongue virus (BTV), a virus with a segmented dsRNA genome belonging to the family Reoviridae, genus Orbivirus. BTV is transmitted through the bites of Culicoides midges. The aim of this study was to develop a new method for quantification of BTV Seg-10 by droplet digital RT-PCR (RTdd-PCR), using nucleic acids purified from complex matrices such as blood, tissues, and midges, that notoriously contain strong PCR inhibitors. First, RTdd-PCR was optimized by using RNAs purified from serially 10-fold dilutions of a BTV-1 isolate (105.43TCID50/ml up to 10−0.57 TCID50/ml) and from the same dilutions spiked into fresh ovine EDTA-blood and spleen homogenate. The method showed a good degree of linearity (R2 ≥ 0.995). The limit of detection (LoD) and the limit of quantification (LoQ) established were 10−0.67TCID50/ml (0.72 copies/μl) and 100.03TCID50/ml (3.05 copies/μl) of BTV-1, respectively. Second, the newly developed test was compared, using the same set of biological samples, to the quantitative RT-PCR (RT-qPCR) detecting Seg-10 assay widely used for the molecular diagnosis of BTV from field samples. Results showed a difference mean of 0.30 log between the two assays with these samples (p < 0.05). Anyway, the analysis of correlation demonstrated that both assays provided similar measurements with a very close agreement between the systems.
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Affiliation(s)
- Angela M Rocchigiani
- Department of Sanità Animale, Istituto Zooprofilattico Sperimentale Della Sardegna, Sassari, Italy
| | - Maria G Tilocca
- Department of Sanità Animale, Istituto Zooprofilattico Sperimentale Della Sardegna, Sassari, Italy
| | - Ottavio Portanti
- OIE Reference Laboratory for Bluetongue, Istituto Zooprofilattico Sperimentale Abruzzo e Molise, Teramo, Italy
| | - Bruna Vodret
- Department of Sanità Animale, Istituto Zooprofilattico Sperimentale Della Sardegna, Sassari, Italy
| | - Roberto Bechere
- Department of Sanità Animale, Istituto Zooprofilattico Sperimentale Della Sardegna, Sassari, Italy
| | - Marco Di Domenico
- OIE Reference Laboratory for Bluetongue, Istituto Zooprofilattico Sperimentale Abruzzo e Molise, Teramo, Italy
| | - Giovanni Savini
- OIE Reference Laboratory for Bluetongue, Istituto Zooprofilattico Sperimentale Abruzzo e Molise, Teramo, Italy
| | - Alessio Lorusso
- OIE Reference Laboratory for Bluetongue, Istituto Zooprofilattico Sperimentale Abruzzo e Molise, Teramo, Italy
| | - Giantonella Puggioni
- Department of Sanità Animale, Istituto Zooprofilattico Sperimentale Della Sardegna, Sassari, Italy
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19
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Bogožalec Košir A, Cvelbar T, Kammel M, Grunert HP, Zeichhardt H, Milavec M. Digital PCR method for detection and quantification of specific antimicrobial drug-resistance mutations in human cytomegalovirus. J Virol Methods 2020; 281:113864. [PMID: 32380093 DOI: 10.1016/j.jviromet.2020.113864] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 04/06/2020] [Accepted: 04/08/2020] [Indexed: 12/18/2022]
Abstract
Antimicrobial drug resistance is one of the biggest threats to human health worldwide. Timely detection and quantification of infectious agents and their susceptibility to antimicrobial drugs are crucial for efficient management of resistance to antiviral drugs. In clinical settings, viral drug resistance is most often associated with prolonged treatment of chronic infections, and assessed by genotyping methods; e.g., sequencing and PCR. These approaches have limitations: sequencing can be expensive and does not provide quantification; and qPCR quantification is hampered by a lack of reference materials for standard curves. In recent years, digital PCR has been introduced, which provides absolute quantification without the need for reference materials for standard curves. Using digital PCR, we have developed a rapid, sensitive and accurate method for genotyping and quantification of the most prevalent mutations that cause human cytomegalovirus resistance to ganciclovir.
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Affiliation(s)
- Alexandra Bogožalec Košir
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna Pot 111, 1000 Ljubljana, Slovenia
| | - Tašja Cvelbar
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia
| | - Martin Kammel
- INSTAND, Gesellschaft Zur Förderung Der Qualitätssicherung in Medizinischen Laboratorien e.V. Ubierstr.20, 40223 Düsseldorf, Germany; IQVD GmbH, Institut Für Qualitätssicherung in Der Virusdiagnostik, Potsdamer Chaussee 80, 14129 Berlin, Germany
| | - Hans-Peter Grunert
- GBD Gesellschaft Für Biotechnologische Diagnostik mbH, Potsdamer Chaussee 80, 14129 Berlin, Germany
| | - Heinz Zeichhardt
- INSTAND, Gesellschaft Zur Förderung Der Qualitätssicherung in Medizinischen Laboratorien e.V. Ubierstr.20, 40223 Düsseldorf, Germany; IQVD GmbH, Institut Für Qualitätssicherung in Der Virusdiagnostik, Potsdamer Chaussee 80, 14129 Berlin, Germany; GBD Gesellschaft Für Biotechnologische Diagnostik mbH, Potsdamer Chaussee 80, 14129 Berlin, Germany
| | - Mojca Milavec
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna Pot 111, 1000 Ljubljana, Slovenia.
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20
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Dobnik D, Kogovšek P, Jakomin T, Košir N, Tušek Žnidarič M, Leskovec M, Kaminsky SM, Mostrom J, Lee H, Ravnikar M. Accurate Quantification and Characterization of Adeno-Associated Viral Vectors. Front Microbiol 2019; 10:1570. [PMID: 31379763 PMCID: PMC6650692 DOI: 10.3389/fmicb.2019.01570] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 06/24/2019] [Indexed: 12/18/2022] Open
Abstract
One of the main challenges in the gene therapy viral vector development is to establish an optimized process for its large scale production. This requires optimization for upstream and downstream processes as well as methods that enable the step-by step analytical characterization of the virus, the results of which inform the iterative refinement of production for yield, purity and potency. The biggest problem here is a plethora of viral vector formulations, many of which interfere with analytical techniques. We took adeno-associated virus (AAV) as an example and showed benefits of combined use of molecular methods and transmission electron microscopy (TEM) for viral vectors' characterization and quantification. Results of the analyses showed that droplet digital PCR (ddPCR) performs better than quantitative real-time PCR (qPCR), in terms of robustness and assay variance, and this was especially relevant for partially purified (in-process) samples. Moreover, we demonstrate the importance of sample preparation prior to PCR analysis. We evaluated viral structure, presence of aggregates and impurities with TEM analysis and found that these impacted the differences in viral titers observed by qPCR and ddPCR and could be altered by sample preparation. These results serve as a guide for the establishment of the analytical methods required to provide measures of identity and purity for AAV viral vectors.
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Affiliation(s)
- David Dobnik
- Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia
| | - Polona Kogovšek
- Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia
| | - Tjaša Jakomin
- Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia
| | - Nejc Košir
- Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia
| | - Magda Tušek Žnidarič
- Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia
| | | | - Stephen M. Kaminsky
- Belfer Gene Therapy Core Facility, Department of Genetic Medicine, Weill Medical College of Cornell University, New York, NY, United States
| | - Janet Mostrom
- Belfer Gene Therapy Core Facility, Department of Genetic Medicine, Weill Medical College of Cornell University, New York, NY, United States
| | - Hyunmi Lee
- Belfer Gene Therapy Core Facility, Department of Genetic Medicine, Weill Medical College of Cornell University, New York, NY, United States
| | - Maja Ravnikar
- Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia
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21
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Kaushik AM, Hsieh K, Wang TH. Droplet microfluidics for high-sensitivity and high-throughput detection and screening of disease biomarkers. WILEY INTERDISCIPLINARY REVIEWS. NANOMEDICINE AND NANOBIOTECHNOLOGY 2018; 10:e1522. [PMID: 29797414 PMCID: PMC6185786 DOI: 10.1002/wnan.1522] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 03/02/2018] [Accepted: 03/10/2018] [Indexed: 12/17/2022]
Abstract
Biomarkers are nucleic acids, proteins, single cells, or small molecules in human tissues or biological fluids whose reliable detection can be used to confirm or predict disease and disease states. Sensitive detection of biomarkers is therefore critical in a variety of applications including disease diagnostics, therapeutics, and drug screening. Unfortunately for many diseases, low abundance of biomarkers in human samples and low sample volumes render standard benchtop platforms like 96-well plates ineffective for reliable detection and screening. Discretization of bulk samples into a large number of small volumes (fL-nL) via droplet microfluidic technology offers a promising solution for high-sensitivity and high-throughput detection and screening of biomarkers. Several microfluidic strategies exist for high-throughput biomarker digitization into droplets, and these strategies have been utilized by numerous droplet platforms for nucleic acid, protein, and single-cell detection and screening. While the potential of droplet-based platforms has led to burgeoning interest in droplets, seamless integration of sample preparation technologies and automation of platforms from biological sample to answer remain critical components that can render these platforms useful in the clinical setting in the near future. This article is categorized under: Diagnostic Tools > Biosensing Diagnostic Tools > Diagnostic Nanodevices Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.
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Affiliation(s)
| | - Kuangwen Hsieh
- Department of Mechanical Engineering, Johns Hopkins University
| | - Tza-Huei Wang
- Department of Mechanical Engineering, Department of Biomedical Engineering, Johns Hopkins University
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22
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Yang D, Hu T, Wu X, Li K, Zhong Q, Liu W. Droplet-digital polymerase chain reaction for detection of clinical hepatitis B virus DNA samples. J Med Virol 2018; 90:1868-1874. [PMID: 30085351 DOI: 10.1002/jmv.25276] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 07/07/2018] [Indexed: 12/26/2022]
Abstract
This study aimed to establish a quantitative droplet-digital polymerase chain reaction (ddPCR) detection system for clinical hepatitis B virus (HBV) DNA in samples from patients with HBV infection with the aim of monitoring fluctuations and planning future antiviral treatments. Primers and probes for the conserved region of HBV DNA sequence (GenBank: AB554017.1) were designed by sequence alignment with the HBV DNA sequence in GenBank. The PUC57 plasmid containing the gene fragment was then synthesized according to the fragment amplified by the primer. Linear DNA templates were obtained by digestion of the PUC57 plasmid with EcoRI. Primer specificity was verified by electrophoresis and sequencing, and the plasmid was used to verify the performance of ddPCR. Serum levels of HBV DNA were then detected in 103 HBV patients by ddPCR and real-time quantitative polymerase chain reaction (qPCR), and the consistency of the two methods was compared. The accuracy of the ddPCR assays showed good linear correlation (R2 = 0.9952). The ddPCR coefficient of variance (CV) for intrarun replicates reached 2.0%, and the CV value for inter-run replicates reached 3.6%. The ddPCR could detect as little as one copy of the template, as demonstrated by continuous dilution. This assay system provided a novel and specific platform with a linear range of detection from 1 to 105 copies/µL. Serum samples were collected from 103 HBV patients, and HBV DNA levels quantified by ddPCR and qPCR showed good concordance based on the Bland-Altman analysis. The 95% limits of agreement were log10 : 0.29 ± 0.55 copies/μL. Our findings demonstrated that ddPCR can improve the detection level of nucleic acid and quantify the nucleic acid concentration, which is suitable for the clinical detection of HBV DNA.
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Affiliation(s)
- Deping Yang
- Central Laboratory, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China.,Department of Laboratory Medicine, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China.,Department of Laboratory Medicine, Shanghai University of Medicine & Health Sciences Affiliated Zhoupu Hospital, Shanghai, China
| | - Tingting Hu
- Department of Laboratory Medicine, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Xuan Wu
- Department of Laboratory Medicine, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - Ke Li
- Department of Laboratory Medicine, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - Qi Zhong
- Department of Laboratory Medicine, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China.,Department of Laboratory Medicine, Shanghai Skin Disease Hospital, Tongji University, Shanghai, China
| | - Weiwei Liu
- Central Laboratory, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China.,Department of Laboratory Medicine, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China.,Department of Laboratory Medicine, Shanghai Skin Disease Hospital, Tongji University, Shanghai, China
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23
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Bosman KJ, Wensing AMJ, Pijning AE, van Snippenberg WJ, van Ham PM, de Jong DMC, Hoepelman AIM, Nijhuis M. Development of sensitive ddPCR assays to reliably quantify the proviral DNA reservoir in all common circulating HIV subtypes and recombinant forms. J Int AIDS Soc 2018; 21:e25185. [PMID: 30375818 PMCID: PMC6138437 DOI: 10.1002/jia2.25185] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 08/17/2018] [Indexed: 12/21/2022] Open
Abstract
INTRODUCTION The latent reservoir is the main barrier on the road to HIV cure, and clinical approaches towards eradication are often evaluated by their effect on proviral DNA. To ensure inclusiveness and representativeness in HIV cure studies, proviral DNA quantification assays that are able to detect all common circulating HIV clades are urgently needed. Here, three HIV DNA assays targeting three different genomic regions were evaluated for their sensitivity and subtype-tolerance using digital PCR. METHODS A subtype-B-specific assay targeting gag (GAG) and two assays targeting conserved sequences in ltr and pol (LTR and JO) were assessed for their sensitivity and subtype-tolerance in digital PCR (Bio-Rad QX200), using a panel of serially diluted subtype reference plasmids as well as a panel of clinical isolates. Both panels represent subtypes A, B, C, D, F, G and circulating recombinant forms (CRFs) AE and AG, which together are responsible for 94% of HIV infections worldwide. RESULTS HIV subtype was observed to greatly affect HIV DNA quantification results. Robust regression analysis of the serially diluted plasmid panel showed that the GAG assay was only able to linearly quantify subtype B, D and G isolates (4/13 reference plasmids, average R2 = 0.99), whereas LTR and JO were able to quantify all tested isolates (13/13 reference plasmids, respective average R2 = 0.99 and 0.98). In the clinical isolates panel, isolates were considered detectable if all replicates produced a positive result. The GAG assay could detect HIV DNA in four out of five subtype B and one out of two subtype D isolates, whereas the LTR and JO assays detected HIV DNA in all twenty-nine tested isolates. LTR and JO results were found to be equally precise but more precise than GAG. CONCLUSIONS The results demonstrate the need for a careful validation of proviral reservoir quantification assays prior to investigations into non-B subtype reservoirs. The LTR and JO assays can sensitively and reliably quantify HIV DNA in a panel that represents the worldwide most prevalent subtypes and CRFs (A, B, C, D, AE, F, G and AG), justifying their application in future trials aimed at global HIV cure.
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Affiliation(s)
- Kobus J Bosman
- Department of Medical MicrobiologyUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Annemarie MJ Wensing
- Department of Medical MicrobiologyUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Aster E Pijning
- Department of Medical MicrobiologyUniversity Medical Center UtrechtUtrechtthe Netherlands
| | | | - Petra M van Ham
- Department of Medical MicrobiologyUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Dorien MC de Jong
- Department of Medical MicrobiologyUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Andy IM Hoepelman
- Department of Internal Medicine and Infectious DiseasesUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Monique Nijhuis
- Department of Medical MicrobiologyUniversity Medical Center UtrechtUtrechtthe Netherlands
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Powell EA, Babady NE. Digital PCR in the Clinical Microbiology Laboratory: Another Tool on the Molecular Horizon. ACTA ACUST UNITED AC 2018. [DOI: 10.1016/j.clinmicnews.2018.01.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Wong K, Molina M. Applying Quantitative Molecular Tools for Virus Transport Studies: Opportunities and Challenges. GROUND WATER 2017; 55:778-783. [PMID: 28542984 PMCID: PMC6146963 DOI: 10.1111/gwat.12531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 04/02/2017] [Accepted: 04/05/2017] [Indexed: 05/31/2023]
Abstract
Bacteriophages have been used in soil column studies for the last several decades as surrogates to study the fate and transport behavior of enteric viruses in groundwater. However, recent studies have shown that the transport behavior of bacteriophages and enteric viruses in porous media can be very different. The next generation of virus transport science must therefore provide more data on mobility of enteric viruses and the relationship between transport behaviors of enteric viruses and bacteriophages. To achieve this new paradigm, labor intensity devoted to enteric virus quantification method must be reduced. Recent studies applied quantitative polymerase chain reaction (qPCR) to column filtration experiments to study the transport behavior of human adenovirus (HAdV) in porous media under a variety of conditions. A similar approach can be used to study the transport of other enteric viruses such as norovirus. Analyzing the column samples with both qPCR and culture assays and applying multiplex qPCR to study cotransport behavior of more than one virus will provide information to under-explored areas in virus transport science. Both nucleic acid extraction kits and one-step lysis protocols have been used in these column studies to extract viral nucleic acid for qPCR quantification. The pros and cons of both methods are compared herein and solutions for overcoming problems are suggested. As better understanding of the transport behavior of enteric viruses is clearly needed, we strongly advocate for application of rapid molecular tools in future studies as well as optimization of protocols to overcome their current limitations.
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Affiliation(s)
- Kelvin Wong
- Ecosystem Research Division, USEPA Office of Research and Development, National Exposure Research Laboratory, 960 College Station Road, Athens, GA, 30605
- Oak Ridge Institute for Science and Education, 1299 Bethel Valley Road, Oak Ridge, TN, 37831
| | - Marirosa Molina
- Ecosystem Research Division, USEPA Office of Research and Development, National Exposure Research Laboratory, 960 College Station Road, Athens, GA, 30605
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Droplet volume variability as a critical factor for accuracy of absolute quantification using droplet digital PCR. Anal Bioanal Chem 2017; 409:6689-6697. [PMID: 28921124 PMCID: PMC5670190 DOI: 10.1007/s00216-017-0625-y] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 08/30/2017] [Accepted: 09/05/2017] [Indexed: 11/13/2022]
Abstract
Accurate and precise nucleic-acid quantification is crucial for clinical and diagnostic decisions, as overestimation or underestimation can lead to misguided treatment of a disease or incorrect labelling of the products. Digital PCR is one of the best tools for absolute nucleic-acid copy-number determination. However, digital PCR needs to be well characterised in terms of accuracy and sources of uncertainty. With droplet digital PCR, discrepancies between the droplet volume assigned by the manufacturer and measured by independent laboratories have already been shown in previous studies. In the present study, we report on the results of an inter-laboratory comparison of different methods for droplet volume determination that is based on optical microscopy imaging and is traceable to the International System of Units. This comparison was conducted on the same DNA material, with the examination of the influence of parameters such as droplet generators, supermixes, operators, inter-cartridge and intra-cartridge variability, and droplet measuring protocol. The mean droplet volume was measured using a QX200™ AutoDG™ Droplet Digital™ PCR system and two QX100™ Droplet Digital™ PCR systems. The data show significant volume differences between these two systems, as well as significant differences in volume when different supermixes are used. We also show that both of these droplet generator systems produce droplets with significantly lower droplet volumes (13.1%, 15.9%, respectively) than stated by the manufacturer and previously measured by other laboratories. This indicates that to ensure precise quantification, the droplet volumes should be assessed for each system.
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Abstract
Digital PCR (dPCR) is an important new tool for use in the clinical microbiology laboratory. Its advantages over quantitative PCR (qPCR), including absolute quantification without a standard curve, improved precision, improved accuracy in the presence of inhibitors, and more accurate quantitation when amplification efficiency is low, make dPCR the assay of choice for several specimen testing applications. This minireview will discuss the advantages and disadvantages of dPCR compared to qPCR, its applications in clinical microbiology, and considerations for implementation of the method in a clinical laboratory.
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Inter-laboratory assessment of different digital PCR platforms for quantification of human cytomegalovirus DNA. Anal Bioanal Chem 2017; 409:2601-2614. [PMID: 28124757 PMCID: PMC5359388 DOI: 10.1007/s00216-017-0206-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 01/04/2017] [Accepted: 01/11/2017] [Indexed: 12/24/2022]
Abstract
Quantitative PCR (qPCR) is an important tool in pathogen detection. However, the use of different qPCR components, calibration materials and DNA extraction methods reduces comparability between laboratories, which can result in false diagnosis and discrepancies in patient care. The wider establishment of a metrological framework for nucleic acid tests could improve the degree of standardisation of pathogen detection and the quantification methods applied in the clinical context. To achieve this, accurate methods need to be developed and implemented as reference measurement procedures, and to facilitate characterisation of suitable certified reference materials. Digital PCR (dPCR) has already been used for pathogen quantification by analysing nucleic acids. Although dPCR has the potential to provide robust and accurate quantification of nucleic acids, further assessment of its actual performance characteristics is needed before it can be implemented in a metrological framework, and to allow adequate estimation of measurement uncertainties. Here, four laboratories demonstrated reproducibility (expanded measurement uncertainties below 15%) of dPCR for quantification of DNA from human cytomegalovirus, with no calibration to a common reference material. Using whole-virus material and extracted DNA, an intermediate precision (coefficients of variation below 25%) between three consecutive experiments was noted. Furthermore, discrepancies in estimated mean DNA copy number concentrations between laboratories were less than twofold, with DNA extraction as the main source of variability. These data demonstrate that dPCR offers a repeatable and reproducible method for quantification of viral DNA, and due to its satisfactory performance should be considered as candidate for reference methods for implementation in a metrological framework.
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Clarity™ digital PCR system: a novel platform for absolute quantification of nucleic acids. Anal Bioanal Chem 2016; 409:1869-1875. [DOI: 10.1007/s00216-016-0131-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 11/17/2016] [Accepted: 12/02/2016] [Indexed: 10/20/2022]
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Cao L, Cui X, Hu J, Li Z, Choi JR, Yang Q, Lin M, Ying Hui L, Xu F. Advances in digital polymerase chain reaction (dPCR) and its emerging biomedical applications. Biosens Bioelectron 2016; 90:459-474. [PMID: 27818047 DOI: 10.1016/j.bios.2016.09.082] [Citation(s) in RCA: 169] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 09/23/2016] [Accepted: 09/24/2016] [Indexed: 12/18/2022]
Abstract
Since the invention of polymerase chain reaction (PCR) in 1985, PCR has played a significant role in molecular diagnostics for genetic diseases, pathogens, oncogenes and forensic identification. In the past three decades, PCR has evolved from end-point PCR, through real-time PCR, to its current version, which is the absolute quantitive digital PCR (dPCR). In this review, we first discuss the principles of all key steps of dPCR, i.e., sample dispersion, amplification, and quantification, covering commercialized apparatuses and other devices still under lab development. We highlight the advantages and disadvantages of different technologies based on these steps, and discuss the emerging biomedical applications of dPCR. Finally, we provide a glimpse of the existing challenges and future perspectives for dPCR.
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Affiliation(s)
- Lei Cao
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Xingye Cui
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Jie Hu
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Zedong Li
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Jane Ru Choi
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Qingzhen Yang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Min Lin
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Li Ying Hui
- Foundation of State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing 100094, PR China
| | - Feng Xu
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China.
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Vynck M, Trypsteen W, Thas O, Vandekerckhove L, De Spiegelaere W. The Future of Digital Polymerase Chain Reaction in Virology. Mol Diagn Ther 2016; 20:437-47. [DOI: 10.1007/s40291-016-0224-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Quantitative Assessment of Commutability for Clinical Viral Load Testing Using a Digital PCR-Based Reference Standard. J Clin Microbiol 2016; 54:1616-1623. [PMID: 27076654 DOI: 10.1128/jcm.03346-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 04/05/2016] [Indexed: 11/20/2022] Open
Abstract
Given recent advances in the development of quantitative standards, particularly WHO international standards, efforts to better understand the commutability of reference materials have been made. Existing approaches in evaluating commutability include prediction intervals and correspondence analysis; however, the results obtained from existing approaches may be ambiguous. We have developed a "deviation-from-ideal" (DFI) approach to evaluate commutability of standards and applied it to the assessment of Epstein-Bar virus (EBV) load testing in four quantitative PCR assays, treating digital PCR as a reference assay. We then discuss advantages and limitations of the DFI approach as well as experimental design to best evaluate the commutability of an assay in practice.
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