scholarly journals Amplification-free RNA detection with CRISPR–Cas13

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Hajime Shinoda ◽  
Yuya Taguchi ◽  
Ryoya Nakagawa ◽  
Asami Makino ◽  
Sae Okazaki ◽  
...  
Keyword(s):  
High Specificity ◽  
Emerging Technology ◽  
Detection Sensitivity ◽  
N Gene ◽  
Nucleic Acid Detection ◽  
Rapid Diagnostics ◽  
Rna Detection ◽  
Guide Rnas ◽  
Rna Targets ◽  
Maximal Sensitivity

AbstractCRISPR-based nucleic-acid detection is an emerging technology for molecular diagnostics. However, these methods generally require several hours and could cause amplification errors, due to the pre-amplification of target nucleic acids to enhance the detection sensitivity. Here, we developed a platform that allows “CRISPR-based amplification-free digital RNA detection (SATORI)”, by combining CRISPR-Cas13-based RNA detection and microchamber-array technologies. SATORI detected single-stranded RNA targets with maximal sensitivity of ~10 fM in <5 min, with high specificity. Furthermore, the simultaneous use of multiple different guide RNAs enhanced the sensitivity, thereby enabling the detection of the SARS-CoV-2 N-gene RNA at ~5 fM levels. Therefore, we hope SATORI will serve as a powerful class of accurate and rapid diagnostics.

scholarly journals SARS-CoV-2 RNA Detection with Duplex-Specific Nuclease Signal Amplification

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 197
Author(s):  
Meiqing Liu ◽  
Haoran Li ◽  
Yanwei Jia ◽  
Pui-In Mak ◽  
Rui P. Martins
Keyword(s):  
Signal Amplification ◽  
Incubation Temperature ◽  
Dna Probes ◽  
Detection Sensitivity ◽  
N Gene ◽  
Rna Detection ◽  
Gold Standard Method ◽  
Complementary Method ◽  
Amplification Method ◽  
Virus Rna

The emergence of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a zoonotic pathogen, has led to the outbreak of coronavirus disease 2019 (COVID-19) pandemic and brought serious threats to public health worldwide. The gold standard method for SARS-CoV-2 detection requires both reverse transcription (RT) of the virus RNA to cDNA and then polymerase chain reaction (PCR) for the cDNA amplification, which involves multiple enzymes, multiple reactions and a complicated assay optimization process. Here, we developed a duplex-specific nuclease (DSN)-based signal amplification method for SARS-CoV-2 detection directly from the virus RNA utilizing two specific DNA probes. These specific DNA probes can hybridize to the target RNA at different locations in the nucleocapsid protein gene (N gene) of SARS-CoV-2 to form a DNA/RNA heteroduplex. DSN cleaves the DNA probe to release fluorescence, while leaving the RNA strand intact to be bound to another available probe molecule for further cleavage and fluorescent signal amplification. The optimized DSN amount, incubation temperature and incubation time were investigated in this work. Proof-of-principle SARS-CoV-2 detection was demonstrated with a detection sensitivity of 500 pM virus RNA. This simple, rapid, and direct RNA detection method is expected to provide a complementary method for the detection of viruses mutated at the PCR primer-binding regions for a more precise detection.

scholarly journals Clinical validation of colorimetric RT-LAMP, a fast, highly sensitive and specific COVID-19 molecular diagnostic tool that is robust to detect SARS-CoV-2 variants of concern

2021 ◽  
Author(s):  
Pedro Augusto Alves ◽  
Ellen G. Oliveira ◽  
Ana Paula M. Franco-Luiz ◽  
Leticia T. Almeida ◽  
Amanda B. Goncalves ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Rna Extraction ◽  
High Specificity ◽  
Cross Reactivity ◽  
Alternative Methods ◽  
Molecular Diagnostic ◽  
N Gene ◽  
Clinical Validation ◽  
Rna Detection ◽  
Viral Transport Medium

The COVID-19 pandemics unfolded due to the widespread SARS-CoV-2 transmission reinforced the urgent need for affordable molecular diagnostic alternative methods for massive testing screening. We present the clinical validation of a pH-dependent colorimetric RT-LAMP (reverse transcription loop-mediated isothermal amplification) for SARS-CoV-2 detection. The method revealed a limit of detection of 19.3 viral genomic copies/uL when using RNA extracted samples obtained from nasopharyngeal swabs collected in guanidine-containing viral transport medium. Typical RT-LAMP reactions were performed at 65 C for 30 min. When compared to RT-qPCR, up to Ct value 32, RT-LAMP presented 97% (87.4-99.4% 95% CI) sensitivity and 100% (86.2-100%) specificity for SARS-CoV-2 RNA detection targeting N gene. No cross-reactivity was detected when testing other non-SARS-CoV virus, confirming high specificity. The test is compatible with primary RNA extraction free samples. We also demonstrated that colorimetric RT-LAMP can detect SARS-CoV-2 variants of concern (VOC) and variants of interest (VOI), such as variants occurring in Brazil named P.1, P.2, B.1.1.374 and B.1.1.371. The method meets point-of-care requirements and can be deployed in the field for high-throughput COVID-19 testing campaigns, especially in countries where COVID-19 testing efforts are far from ideal to tackle the pandemics. Although RT-qPCR is considered the gold standard for SARS-CoV-2 RNA detection, it requires expensive equipments, infrastructure and highly trained personnel. In contrast, RT-LAMP emerges as an affordable, inexpensive and simple alternative for SARS-CoV-2 molecular detection that can be applied to massive COVID-19 testing campaigns and save lives.

scholarly journals Rapid Detection of SARS-CoV-2 Using Reverse transcription RT-LAMP method

2020 ◽  
Author(s):  
Weihua Yang ◽  
Xiaofei Dang ◽  
Qingxi Wang ◽  
Mingjie Xu ◽  
Qianqian Zhao ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Reverse Transcription ◽  
Virus Disease ◽  
Lamp Assay ◽  
Nucleic Acid Amplification ◽  
N Gene ◽  
Nucleic Acid Detection ◽  
Lamp Method ◽  
Rt Pcr ◽  
Rapid Amplification

AbstractCorona Virus Disease 2019 (COVID-19) is a recently emerged life-threatening disease caused by SARS-CoV-2. Real-time fluorescent PCR (RT-PCR) is the clinical standard for SARS-CoV-2 nucleic acid detection. To detect SARS-CoV-2 early and control the disease spreading on time, a faster and more convenient method for SARS-CoV-2 nucleic acid detecting, RT-LAMP method (reverse transcription loop-mediated isothermal amplification) was developed. RNA reverse transcription and nucleic acid amplification were performed in one step at 63 °C isothermal conditions, and the results can be obtained within 30 minutes. ORF1ab gene, E gene and N gene were detected at the same time. ORF1ab gene was very specific and N gene was very sensitivity, so they can guarantee both sensitivity and specificity for SARS-CoV-2. The sensitivity of RT-LAMP assay is similar to RT-PCR, and specificity was 99% as detecting 208 clinical specimens. The RT-LAMP assay reported here has the advantages of rapid amplification, simple operation, and easy detection, which is useful for the rapid and reliable clinical diagnosis of SARS-CoV-2.

scholarly journals Cancer patient management strategy in a Cancer Center of Zhejiang, China during the COVID-19 pandemic

BMC Cancer ◽  
2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Songxiao Xu ◽  
Xiangdong Cheng ◽  
Zhiwen Pan ◽  
Qian Song ◽  
Yihong Wang ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Infection Control ◽  
Cancer Patients ◽  
Cell Counting ◽  
Clinicopathological Parameters ◽  
N Gene ◽  
Cancer Center ◽  
Nucleic Acid Detection ◽  
Cancer Hospital ◽  
Increased Risk

Abstract Background Due to the increased risk of viral infection and the severe shortage of medical resources during the pandemic of COVID-19, most hospitals in the epidemic areas significantly reduced non-emergency admissions and services, if not closed. As a result, it has been difficult to treat cancer patients on time, which adversely affects their prognosis. To address this problem, cancer centers must develop a strategic plan to manage both inpatients and outpatients during the pandemic, provide them with the necessary treatment, and at the same time prevent the spread of the virus among patients, visitors and medical staff. Methods Based upon the epidemic situation in Zhejiang Province, China, the number of running non-emergency medical wards in the Zhejiang Cancer Hospital was gradually increased in a controlled manner. All staff of the hospital received COVID-19 preventive training and was provided with three different levels of protection according to the risks of their services. Only patients without a known history of SARS-CoV-2 contact were eligible to schedule an appointment. Body temperature was measured on all patients upon their arrival at the hospital. Chest CT image, blood cell counting and travel/contact history were investigated in patients with fever. Respiratory tract samples, such as sputum and throat swabs, from all patients, including those clinically suspected of SARS-CoV-2 infection, were collected for nucleic acid detection of SARS-CoV-2 before treatment. Results A total of 3697 inpatients and 416 outpatients seeking cancer treatment were enrolled from February 1 to April 3, 2020, in compliance with the hospital’s infection-control interventions. The clinicopathological parameters of the patients were summarized herein. 4237 samples from 4101 patients produced negative RNA testing results. Four clinically suspected patients all presented negative RNA test results and were excluded from the SARS-CoV-2 infection through follow-up retesting and monitoring. Seven patients with only N-gene positive results were retested, followed by CT scan and SARS-CoV-2 contact history investigation. All of them were finally diagnosed as non-infected patients. There was one outpatient who was confirmed positive by virus RNA test and then followed up. She might be an asymptomatic laboratory-confirmed case. During the study period, there was no SARS-CoV-2 infection among staff, patients and escorts of patients in the Zhejiang Cancer Hospital. Conclusion This study suggested our infection-control interventions, including viral nucleic acid test, could be used as a reliable method to screen cancer patients in the area with moderate COVID-19 prevalence. Cancer may not be a high-risk factor of SARS-CoV-2 infection.

scholarly journals SARS-CoV-2 RNA Extraction Using Magnetic Beads for Rapid Large-Scale Testing by RT-qPCR and RT-LAMP

Viruses ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 863 ◽  
Author(s):  
Steffen Klein ◽  
Thorsten G. Müller ◽  
Dina Khalid ◽  
Vera Sonntag-Buck ◽  
Anke-Mareil Heuser ◽  
...  
Keyword(s):  
Reverse Transcription ◽  
Large Scale ◽  
Rna Extraction ◽  
Magnetic Bead ◽  
Viral Rna ◽  
Detection Sensitivity ◽  
Detection Methods ◽  
N Gene ◽  
Extraction Protocol ◽  
Large Scale Testing

Rapid large-scale testing is essential for controlling the ongoing pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The standard diagnostic pipeline for testing SARS-CoV-2 presence in patients with an ongoing infection is predominantly based on pharyngeal swabs, from which the viral RNA is extracted using commercial kits, followed by reverse transcription and quantitative PCR detection. As a result of the large demand for testing, commercial RNA extraction kits may be limited and, alternatively, non-commercial protocols are needed. Here, we provide a magnetic bead RNA extraction protocol that is predominantly based on in-house made reagents and is performed in 96-well plates supporting large-scale testing. Magnetic bead RNA extraction was benchmarked against the commercial QIAcube extraction platform. Comparable viral RNA detection sensitivity and specificity were obtained by fluorescent and colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) using a primer set targeting the N gene, as well as RT-qPCR using a primer set targeting the E gene, showing that the RNA extraction protocol presented here can be combined with a variety of detection methods at high throughput. Importantly, the presented diagnostic workflow can be quickly set up in a laboratory without access to an automated pipetting robot.

scholarly journals Shine: To explore specific, sensitive and conserved biomarkers from massive microbial genomic data within intrapopulations.

2021 ◽  
Author(s):  
Cong Ji ◽  
Junbin Jack Shao
Keyword(s):  
False Negative ◽  
Genomic Data ◽  
Cost Effective ◽  
Pcr Primers ◽  
Detection Sensitivity ◽  
Nucleic Acid Detection ◽  
Pathogenic Microorganisms ◽  
New Strategy ◽  
Microbial Genomic ◽  
Species Specific

To improve the quality of nucleic acid detection reagents, we provided a new strategy, Shine, to explore specific, sensitive and conserved biomarkers from massive microbial genomic data within intrapopulations in order to improve detection sensitivity and accuracy. It is obvious that the more comprehensive genomic data are, the more effective the detection biomarkers. Here, we demonstrated that our method could detect undiscovered multicopy conserved species-specific or even subspecies-specific target fragments, according to several clinical projects. In particular, this approach was effective for any pathogenic microorganism even in incompletely assembled motifs. Based on our strategy, the detection device designed with quantitative PCR primers and probes for systematic and automated detection of pathogenic microorganisms in biological samples may cover all pathogenic microorganisms without limits based on genome annotation. On the website https://bioinfo.liferiver.com.cn, users may select different configuration parameters depending on the purpose of the project to realize routine clinical detection practices. Therefore, it is recommended that our strategy is suitable to identify shared universal phylogenetic markers with few false positive or false negative errors and to automate the design of minimal primers and probes to detect pathogenic communities with cost-effective predictive power.

scholarly journals One-Tube SARS-CoV-2 Detection Platform Based on RT-RPA and CRISPR/Cas12a

2020 ◽  
Author(s):  
Yangyang Sun ◽  
Lei Yu ◽  
Chengxi Liu ◽  
Wei Chen ◽  
Dechang Li ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Limit Of Detection ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
N Gene ◽  
Clinical Samples ◽  
Nucleic Acid Detection ◽  
Detection Process ◽  
Human Coronaviruses ◽  
Negative Controls

Abstract Background: COVID-19 has spread rapidly around the world, affecting almost every person. When lifting certain mandatory measures for an economic restart, robust surveillance must be established and implemented, with nucleic acid detection for SARS-CoV-2 as an essential component. Methods: We designed RT-RPA (Reverse Transcription and Recombinase Polymerase Isothermal Amplification) primers of RdRp gene and N gene according to the SARS-CoV-2 gene sequence. We optimized the components in the reaction so that the detection process could be carried out in one tube. The specificity was demonstrated through detecting nucleic acid samples from seven human coronaviruses. Clinical samples were used to validate the platform and all results were compared to rRT-PCR. RNA standards diluted by different gradients were used to demonstrate the limit of detection. Furthermore, we have developed a lateral flow assay based on OR-DETECTR for the detection of COVID-19. Results: We have developed a o ne-tube detection platform based on R T- R PA and DNA Endonuclease-Targeted CRISPR Trans Reporter ( DETECTR ) technology, termed OR-DETECTR, to detect SARS-CoV-2. The detection process is completed in one tube, and the time is 50min. The method can specifically detect SARS-CoV-2 from seven human coronaviruses with a low detection limit of 2.5 copies/µl input. Results from six SARS-CoV-2 patient samples, eight samples from patients with fever but no SARS-CoV-2 infection, and one mixed sample from 40 negative controls showed that OR-DETECTR is 100% consistent with rRT-PCR. Furthermore, we have developed a lateral flow assay based on OR-DETECTR for the detection of COVID-19. Conclusions: OR-DETECTR detection platform is rapid, accurate, tube closed, easy-to-operate, and free of large instruments for COVID-19 detection.

scholarly journals A Chemical-Enhanced System for CRISPR-Based Nucleic Acid Detection

2021 ◽  
Author(s):  
Zihan Li ◽  
Wenchang Zhao ◽  
Shixin Ma ◽  
Zexu Li ◽  
Yingjia Yao ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Detection System ◽  
Point Of Care ◽  
Detection Sensitivity ◽  
Nucleic Acid Detection ◽  
Chemical Additives ◽  
Lateral Flow Strip ◽  
Viral Pathogens ◽  
Detection Systems ◽  
System Robustness

The CRISPR-based nucleic acid detection systems such as SHERLOCK, DETECTR and HOLMES have shown great potential for point-of-care testing of viral pathogens, especially in the context of COVID-19 pandemic. Here we optimize several key parameters of reaction chemistry and develop a Chemical Enhanced CRISPR Detection system for nucleic acid (termed CECRID). For the Cas12a/Cas13a-based signal detection phase, we determine buffer conditions and substrate range for optimal detection performance. By comparing several chemical additives, we find that addition of L-proline can secure or enhance Cas12a/Cas13a detection capability. For isothermal amplification phase with typical LAMP and RPA methods, inclusion of L-proline can also enhance specific target amplification as determined by CRISPR detection. Using SARS-CoV-2 pseudovirus, we demonstrate CECRID has enhanced detection sensitivity over chemical additive-null method with either fluorescence or lateral flow strip readout. Thus, CECRID provides an improved detection power and system robustness towards practical application of CRISPR-based diagnostics.

scholarly journals Viability RT-PCR for SARS-CoV-2: a step forward to solve the infectivity quandary

2021 ◽  
Author(s):  
Enric Cuevas-Ferrando ◽  
Walter Randazzo ◽  
Alba Pérez-Cataluña ◽  
Irene Falcó ◽  
David Navarro ◽  
...  
Keyword(s):  
Prevention And Control ◽  
Infection Risk ◽  
Contact Tracing ◽  
Platinum Compounds ◽  
Rt Pcr ◽  
Rna Detection ◽  
Viral Shedding ◽  
Rna Targets ◽  
Wastewater Samples ◽  
And Control

SummaryBackgroundIsolation, contact tracing and restrictions on social movement are being globally implemented to prevent and control onward spread of SARS-CoV-2, even though the infection risk modelled on RNA detection by RT-qPCR remains biased as viral shedding and infectivity are not discerned. Thus, we aimed to develop a rapid viability RT-qPCR procedure to infer SARS-CoV-2 infectivity in clinical specimens and environmental samples.MethodsWe screened monoazide dyes and platinum compounds as viability molecular markers on five SARS-CoV-2 RNA targets. A platinum chloride-based viability RT-qPCR was then optimized using genomic RNA, and inactivated SARS-CoV-2 particles inoculated in buffer, stool, and urine. Our results were finally validated in nasopharyngeal swabs from persons who tested positive for COVID-19 and in wastewater samples positive for SARS-CoV-2 RNA.FindingsWe established a rapid viability RT-qPCR that selectively detects potentially infectious SARS-CoV-2 particles in complex matrices. In particular, the confirmed positivity of nasopharyngeal swabs following the viability procedure suggests their potential infectivity, while the complete prevention of amplification in wastewater indicated either non-infectious particles or free RNA.InterpretationThe viability RT-qPCR approach provides a more accurate ascertainment of the infectious viruses detection and it may complement analyses to foster risk-based investigations for the prevention and control of new or re-occurring outbreaks with a broad application spectrum.FundingsThis work was supported by Spanish Scientific Research Council (CSIC), Generalitat Valenciana, and MICINN co-founded by AEI/FEDER, UE.

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