Validation of saliva sampling as an alternative to oro-nasopharyngeal swab for detection of SARS-CoV-2 using unextracted rRT-PCR with the Allplex 2019-nCoV assay

Introduction. The current severe acute respiratory syndrome-associated coronavirus-2 (SARS-CoV-2) pandemic has stressed the global supply chain for specialized equipment, including flocked swabs. Hypothesis. Saliva could be a potential alternative specimen source for diagnosis of SARS-CoV-2 infection by reverse-transcriptase PCR (RT-PCR). Aim. To compare the detection efficiency of SARS-CoV-2 RNA in saliva and oro-nasopharyngeal swab (ONPS) specimens. Methodology. Patients recruited from hospital provided paired saliva and ONPS specimens. We performed manual or automated RT-PCR with prior proteinase K treatment without RNA extraction using the Seegene Allplex 2019 nCoV assay. Results. Of the 773 specimen pairs, 165 (21.3 %) had at least one positive sample. Additionally, 138 specimens tested positive by both sampling methods. Fifteen and 12 cases were detected only by nasopharyngeal swab and saliva, respectively. The sensitivity of ONPS (153/165; 92.7 %; 95 % CI: 88.8–96.7) was similar to that of saliva (150/165; 90.9 %; 95 % CI: 86.5–95.3; P=0.5). In patients with symptoms for ≤ 10 days, the sensitivity of ONPS (118/126; 93.7 %; 95 % CI: 89.4–97.9) was similar to that of saliva (122/126; 96.8 %; 95 % CI: 93.8–99.9 %; P=0.9). However, the sensitivity of ONPS (20/22; 95.2 %; 95 % CI: 86.1–100) was higher than that of saliva (16/22; 71.4 %; 95 % CI: 52.1–90.8) in patients with symptoms for more than 10 days. Conclusions. Saliva sampling is an acceptable alternative to ONPS for diagnosing SARS-CoV-2 infection in symptomatic individuals displaying symptoms for ≤ 10 days. These results reinforce the need to expand the use of saliva samples, which are self-collected and do not require swabs.

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A faster and less costly alternative for RNA extraction of SARS-CoV-2 using proteinase k treatment followed by thermal shock

PLoS ONE ◽

10.1371/journal.pone.0248885 ◽

2021 ◽

Vol 16 (3) ◽

pp. e0248885

Author(s):

Adolfo Marcelo Ñique ◽

Fiorella Coronado-Marquina ◽

Jairo Andrés Mendez Rico ◽

María Paquita García Mendoza ◽

Nancy Rojas-Serrano ◽

...

Keyword(s):

Thermal Shock ◽

Real Time ◽

Internal Control ◽

Rna Extraction ◽

Cost Effective ◽

Proteinase K ◽

Rt Pcr ◽

Critical Material ◽

Proteinase K Treatment ◽

Commercial Kit

One of the biggest challenges during the pandemic has been obtaining and maintaining critical material to conduct the increasing demand for molecular tests. Sometimes, the lack of suppliers and the global shortage of these reagents, a consequence of the high demand, make it difficult to detect and diagnose patients with suspected SARS-CoV-2 infection, negatively impacting the control of virus spread. Many alternatives have enabled the continuous processing of samples and have presented a decrease in time and cost. These measures thus allow broad testing of the population and should be ideal for controlling the disease. In this sense, we compared the SARS-CoV-2 molecular detection effectiveness by Real time RT-PCR using two different protocols for RNA extraction. The experiments were conducted in the National Institute of Health (INS) from Peru. We compared Ct values average (experimental triplicate) results from two different targets, a viral and internal control. All samples were extracted in parallel using a commercial kit and our alternative protocol–samples submitted to proteinase K treatment (3 μg/μL, 56°C for 10 minutes) followed by thermal shock (98°C for 5 minutes followed by 4°C for 2 minutes); the agreement between results was 100% in the samples tested. In addition, we compared the COVID-19 positivity between six epidemiological weeks: the initial two in that the Real time RT-PCR reactions were conducted using RNA extracted by commercial kit, followed by two other using RNA obtained by our kit-free method, and the last two using kit once again; they did not differ significantly. We concluded that our in-house method is an easy, fast, and cost-effective alternative method for extracting RNA and conducing molecular diagnosis of COVID-19.

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Effective optimization of SARS-CoV-2 laboratory testing variables in an era of supply chain constraints

Future Microbiology ◽

10.2217/fmb-2020-0094 ◽

2020 ◽

Vol 15 (15) ◽

pp. 1483-1487

Author(s):

Nikhil S Sahajpal ◽

Ashis K Mondal ◽

Allan Njau ◽

Sudha Ananth ◽

Kimya Jones ◽

...

Keyword(s):

Supply Chain ◽

Rna Extraction ◽

Nasopharyngeal Swab ◽

Sample Collection ◽

Rt Pcr ◽

Pcr Assay ◽

Short Supply ◽

Viral Transport ◽

3D Printed ◽

Bridging Studies

RT-PCR-based assays for the detection of SARS-CoV-2 have played an essential role in the current COVID-19 pandemic. However, the sample collection and test reagents are in short supply, primarily due to supply chain issues. Thus, to eliminate testing constraints, we have optimized three key process variables: RNA extraction and RT-PCR reactions, different sample types and media to facilitate SARS-CoV-2 testing. By performing various validation and bridging studies, we have shown that various sample types such as nasopharyngeal swab, bronchioalveolar lavage and saliva, collected using conventional nasopharyngeal swabs, ESwab or 3D-printed swabs and, preserved in viral transport media, universal transport media, 0.9% sodium chloride or Amies media are compatible with RT-PCR assay for COVID-19. Besides, the reduction of PCR reagents by up to fourfold also produces reliable results.

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Evaluation of an Automated High-Throughput Liquid-Based RNA Extraction Platform on Pooled Nasopharyngeal or Saliva Specimens for SARS-CoV-2 RT-PCR

Viruses ◽

10.3390/v13040615 ◽

2021 ◽

Vol 13 (4) ◽

pp. 615

Author(s):

Allen Wing-Ho Chu ◽

Cyril Chik-Yan Yip ◽

Wan-Mui Chan ◽

Anthony Chin-Ki Ng ◽

Dream Lok-Sze Chan ◽

...

Keyword(s):

Nucleic Acid ◽

High Throughput ◽

Rna Extraction ◽

Nasopharyngeal Swab ◽

Acid Extraction ◽

Rt Pcr ◽

Nucleic Acid Extraction ◽

Suitable Alternative ◽

Pcr Inhibitors ◽

Pcr Targeting

SARS-CoV-2 RT-PCR with pooled specimens has been implemented during the COVID-19 pandemic as a cost- and manpower-saving strategy for large-scale testing. However, there is a paucity of data on the efficiency of different nucleic acid extraction platforms on pooled specimens. This study compared a novel automated high-throughput liquid-based RNA extraction (LRE) platform (PHASIFYTM) with a widely used magnetic bead-based total nucleic acid extraction (MBTE) platform (NucliSENS® easyMAG®). A total of 60 pools of nasopharyngeal swab and 60 pools of posterior oropharyngeal saliva specimens, each consisting of 1 SARS-CoV-2 positive and 9 SARS-CoV-2 negative specimens, were included for the comparison. Real-time RT-PCR targeting the SARS-CoV-2 RdRp/Hel gene was performed, and GAPDH RT-PCR was used to detect RT-PCR inhibitors. No significant differences were observed in the Ct values and overall RT-PCR positive rates between LRE and MBTE platforms (92.5% (111/120] vs 90% (108/120]), but there was a slightly higher positive rate for LRE (88.3% (53/60]) than MBTE (81.7% (49/60]) among pooled saliva. The automated LRE method is comparable to a standard MBTE method for the detection of SAR-CoV-2 in pooled specimens, providing a suitable alternative automated extraction platform. Furthermore, LRE may be better suited for pooled saliva specimens due to more efficient removal of RT-PCR inhibitors.

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Comparison Between a Standard and SalivaDirect RNA Extraction Protocol for Molecular Diagnosis of SARS-CoV-2 Using Nasopharyngeal Swab and Saliva Clinical Samples

Frontiers in Bioengineering and Biotechnology ◽

10.3389/fbioe.2021.638902 ◽

2021 ◽

Vol 9 ◽

Author(s):

Sofía N. Rodríguez Flores ◽

Luis Mario Rodríguez-Martínez ◽

Bernardita L. Reyes-Berrones ◽

Nadia A. Fernández-Santos ◽

Elthon J. Sierra-Moncada ◽

...

Keyword(s):

Rna Extraction ◽

Proteinase K ◽

Clinical Samples ◽

Nasopharyngeal Swab ◽

Acid Extraction ◽

Sample Collection ◽

Extraction Protocol ◽

Assay Performance ◽

Two Samples ◽

Oropharyngeal Swab

During the COVID-19 pandemic, a certified laboratory of Tamaulipas, Mexico has processed over 100,000 samples of COVID-19 suspected patients, working a minimum of 100 tests daily. Thus, it would be beneficial for such certified laboratories nationwide to reduce the time and cost involved in performing the diagnosis of COVID-19, from sample collection, transportation to local lab, processing of samples, and data acquisition. Here, 30 nasopharyngeal swab and saliva samples from the same COVID-19 individuals were assessed by a standard nucleic acid extraction protocol, including protein lysis with proteinase K followed by binding to column, washing, and elution, and by the SalivaDirect protocol based on protein lysis, skipping the other steps to reduce processing time and costs. The genomic RNA was amplified using a SARS-CoV-2 Real-Time PCR kit. A variation (P > 0.05) in the 95% CIs = 72.6%–96.7% was noted by using the SalivaDirect protocol and saliva samples (sensitivity of 88.2%) in comparison to those of standard protocol with oropharyngeal swab samples (95% CIs = 97.5%–100%; sensitivity of 100%) as reported elsewhere. However, when using nasopharyngeal swab samples in the SalivaDirect protocol (sensitivity of 93.6%; 95% CIs = 79.2%–99.2%), it was in concordance (P < 0.05) with those of the standard one. The logical explanation to this was that two samples with Ct values of 38, and 40 cycles for gene E produced two false negatives in the SalivaDirect protocol in relation to the standard one; thus, there was a reduction of the sensitivity of 6.4% in the overall assay performance.

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Self-collected gargle specimen as a patient-friendly sample collection method for COVID-19 diagnosis in a population context

10.21203/rs.3.rs-764442/v3 ◽

2021 ◽

Author(s):

Revata Utama ◽

Rebriarina Hapsari ◽

Iva Puspitasari ◽

Desvita Sari ◽

Meita Hendrianingtyas ◽

...

Keyword(s):

Healthcare Workers ◽

Room Temperature ◽

Rna Extraction ◽

User Preference ◽

Sample Collection ◽

Rt Pcr ◽

Collection Method ◽

Qrt Pcr ◽

Alternative Specimen ◽

Temperature Storage

Abstract Scaling up SARS-CoV-2 testing and tracing continues to be plagued with the limitation of the sample collection method, which requires trained healthcare workers to perform and causes discomfort to the patients. In response, we assessed the performance and user preference of gargle specimens for qRT-PCR-based detection of SARS-CoV-2 in Indonesia. Inpatients who had recently been diagnosed with COVID-19 and outpatients who were about to perform qRT-PCR testing were asked to provide nasopharyngeal and oropharyngeal (NPOP) swabs and self-collected gargle specimens. We demonstrated that self-collected gargle specimens can be an alternative specimen to detect SARS-CoV-2 and the viral RNA remained stable for 31 days at room temperature storage. The developed method was validated for use on multiple RNA extraction kits and commercially available COVID-19 RT-PCR kits. Our developed method achieved a sensitivity of 91.38% when compared to paired NPOP swab specimens (Ct < 35), with 97.10% of patients preferring the self-collected gargle method.

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Pooling for SARS-CoV-2 Control in Care Institutions

10.21203/rs.3.rs-42489/v1 ◽

2020 ◽

Author(s):

Jorge J. Cabrera Alvargonzalez ◽

Sonia Rey Cao ◽

Sonia Pérez Castro ◽

Lucía Martínez Lamas ◽

Olaia Cores Calvo ◽

...

Keyword(s):

Scale Up ◽

Positive Sample ◽

Care Homes ◽

Nasopharyngeal Swab ◽

Rt Pcr ◽

Average Delay ◽

Global Rate ◽

Local Experience ◽

Expected Performance ◽

Pooling Strategies

Abstract Background Workers and residents in Care Homes are considered at special risk for the acquisition of SARS-CoV-2 infection, due to the infectivity and high mortality rate in the case of residents, compared to other containment areas. The role of presymptomatic people in transmission has been shown to be important and the early detection these people is critical for the control of new outbreaks. Pooling strategies have proven to preserve SARS-CoV-2 testing resources.The aims of the present study, based in our local experience, were (a) to describe SARS-CoV-2 prevalence in institutionalized people in Galicia (Spain) during the Coronavirus pandemic and (b) to evaluate the expected performance of a pooling strategy using RT-PCR for the next rounds of screening of institutionalized people.Methods 25,386 Nasopharyngeal swab samples from the total of the residents and workers at Care Homes in Galicia (March to May 2020) were tested using RT-PCR. Prevalence and distribution of positive detection in Care Homes was calculated. Pools of 19 negative samples and one positive sample were tested using RT-PCR as well. Prevalence and distribution of positive detection in Care Homes was calculated. Results Distribution of SARS-CoV-2 infection at Care Houses was uneven. As the virus circulation global rate was low in our area, the number of people at risk of acquiring the infection continues to be very high. In this work, we have successfully demonstrated that pooling of different groups of samples at low prevalence clusters, can be done with a small average delay on quantification cycle (Cq) values. Conclusions A new surveillance system with guaranteed protection is required for small clusters, previously covered with individual testing. Our proposal for Care Houses, once prevalence zero is achieved, would include successive rounds of testing using a pooling solution for transmission control preserving testing resources. Scale-up of this method may be of utility to confront larger clusters to avoid the viral circulation and keeping them operative.

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Molecular diagnosis of SARS-CoV-2 in seminal fluid

Journal of Endocrinological Investigation ◽

10.1007/s40618-021-01580-x ◽

2021 ◽

Author(s):

D. Paoli ◽

F. Pallotti ◽

G. Nigro ◽

L. Mazzuti ◽

M. N. Hirsch ◽

...

Keyword(s):

Molecular Diagnosis ◽

Seminal Plasma ◽

Reproductive Medicine ◽

Seminal Fluid ◽

Rna Extraction ◽

Nasopharyngeal Swab ◽

Control Panel ◽

Rt Pcr ◽

Sperm Bank ◽

University Of Rome

Abstract Purpose Due to relevant repercussions on reproductive medicine, we aimed to evaluate feasibility of RT-PCR as a detection method of SARS-CoV-2 RNA in seminal fluid. Methods A qualitative determination of the RT-PCR assays in semen was performed through different approaches: (1) efficiency of RNA extraction from sperm and seminal plasma was determined using PRM1 and PRM2 mRNA and a heterologous system as control; (2) samples obtained by diluting viral preparation from a SARS-CoV-2 panel (virus cultured in Vero E6 cell lines) were tested; (3) viral presence in different fractions of seminal fluid (whole sample, seminal plasma and post-centrifugation pellet) was evaluated. Semen samples from mild and recovered COVID-19 subjects were collected by patients referring to the Infectious Disease Department of the Policlinico Umberto I Hospital - “Sapienza” University of Rome. Control subjects were recruited at the Laboratory of Seminology-Sperm Bank “Loredana Gandini'' of the same hospital. Results The control panel using viral preparations diluted in saline and seminal fluid showed the capability to detect viral RNA presence with Ct values depending on the initial viral concentration. All tested semen samples were negative for SARS-CoV-2, regardless of the nasopharyngeal swab result or seminal fluid fraction. Conclusion These preliminary data show that RT-PCR for SARS-CoV-2 RNA testing appears to be a feasible method for the molecular diagnosis of SARS-CoV-2 in seminal fluid, supported by results of the control panel. The ability to detect SARS-CoV-2 in semen is extremely important for reproductive medicine, especially in assisted reproductive technology and sperm cryopreservation.

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Evaluation of RNA extraction free method for detection of SARS-COV-2 in salivary samples for mass screening for COVID-19

10.1101/2021.03.15.21253570 ◽

2021 ◽

Author(s):

Sally A. Mahmoud ◽

Esra Ibrahim ◽

Subhashini Ganesan ◽

Bhagyashree Thakre ◽

Juliet G Teddy ◽

...

Keyword(s):

Sensitivity And Specificity ◽

Gold Standard ◽

Rna Extraction ◽

High Sensitivity ◽

High Specificity ◽

Cost Effective ◽

Kappa Coefficient ◽

Nasopharyngeal Swab ◽

Rt Pcr ◽

Good Percentage

AbstractIn this current COVID - 19 pandemic, there is a dire need for cost effective and less time-consuming alternatives for SARS-COV-2 testing. The RNA extraction free method for detecting SARS-COV-2 in saliva is a promising option, this study found that it has high sensitivity (85.34%), specificity (95.04%) and was comparable to the gold standard nasopharyngeal swab. The method showed good percentage of agreement (kappa coefficient) 0.797 between salivary and NPS samples. However, there are variations in the sensitivity and specificity based on the RT-PCR kit used. The Thermo Fischer-Applied biosystems showed high sensitivity, PPV and NPV but also showed higher percentage of invalid reports. Whereas the BGI kit showed high specificity, better agreement (kappa coefficient) between the results of saliva and NPS samples and higher correlation between the Ct values of saliva and NPS samples. Thus, the RNA extraction free method for salivary sample serves as an effective alternative for SARS-CoV 2-testing.

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A scalable saliva-based, extraction-free rt-lamp protocol for sars-cov-2 diagnosis

10.1101/2020.10.27.20220541 ◽

2020 ◽

Author(s):

Paula Asprino ◽

Fabiana Bettoni ◽

Anamaria Camargo ◽

Diego Coelho ◽

Guilherme Coppini ◽

...

Keyword(s):

Rna Extraction ◽

Cost Effective ◽

Turnaround Time ◽

Curve Analysis ◽

Nasopharyngeal Swab ◽

Screening Methods ◽

Rt Pcr ◽

Effective Screening ◽

Point Curve ◽

Average Turnaround Time

I.ABSTRACTScalable, cost-effective screening methods are an essential tool to control SARS-CoV-2 spread. We have developed a straight saliva-based, RNA extraction-free, RT-LAMP test that is comparable to current nasopharyngeal swab RT-PCR tests in both sensitivity and specificity. Using a 2-step readout of fluorescence and melting-point curve analysis, the test is scalable to more than 30,000 tests per day with average turnaround time of less than 3 hours. The test was validated using samples from 244 symptomatic patients, and showed sensitivity of 78.9% (vs. 85.5% for nasopharyngeal swabs RT-PCR) and specificity of 100% (vs. 100% for nasopharyngeal swabs RT-PCR). Our method is therefore accurate, robust, time and cost effective and therefore can be used for screening of SARS-CoV-2.

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Extraction-free protocol combining proteinase K and heat inactivation for detection of SARS-CoV-2 by RT-qPCR

PLoS ONE ◽

10.1371/journal.pone.0247792 ◽

2021 ◽

Vol 16 (2) ◽

pp. e0247792

Author(s):

Valeria Genoud ◽

Martin Stortz ◽

Ariel Waisman ◽

Bruno G. Berardino ◽

Paula Verneri ◽

...

Keyword(s):

Rna Extraction ◽

Standard Technique ◽

Proteinase K ◽

Clinical Samples ◽

Heat Inactivation ◽

Nasopharyngeal Swab ◽

Reverse Transcription Pcr ◽

Extraction Step ◽

Commercial Kits ◽

Inexpensive Procedure

Real-time reverse transcription PCR (RT-qPCR) is the gold-standard technique for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection in nasopharyngeal swabs specimens. The analysis by RT-qPCR usually requires a previous extraction step to obtain the purified viral RNA. Unfortunately, RNA extraction constitutes a bottleneck for early detection in many countries since it is expensive, time-consuming and depends on the availability of commercial kits. Here, we describe an extraction-free protocol for SARS-CoV-2 detection by RT-qPCR from nasopharyngeal swab clinical samples in saline solution. The method includes a treatment with proteinase K followed by heat inactivation (PK+HID method). We demonstrate that PK+HID improves the RT-qPCR performance in comparison to the heat-inactivation procedure. Moreover, we show that this extraction-free protocol can be combined with a variety of multiplexing RT-qPCR kits. The method combined with a multiplexing detection kit targeting N and ORF1ab viral genes showed a sensitivity of 0.99 and a specificity of 0.99 from the analysis of 106 positive and 106 negative clinical samples. In conclusion, PK+HID is a robust, fast and inexpensive procedure for extraction-free RT-qPCR determinations of SARS-CoV-2. The National Administration of Drugs, Foods and Medical Devices of Argentina has recently authorized the use of this method.

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