Thermal treatment of nasopharyngeal samples before cobas SARS-CoV-2 testing.
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ABSTRACT:
SUBMITTER: Pryce TM
PROVIDER: S-EPMC7409797 | biostudies-literature | 2021 Jan
REPOSITORIES: biostudies-literature
Publications
Thermal treatment of nasopharyngeal samples before cobas SARS-CoV-2 testing.
Pryce Todd M TM Boan Peter A PA Kay Ian D ID Flexman James P JP
Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases 20200806 1
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Project description:To improve laboratory safety we thermally treated naso-oropharyngeal samples before testing with the cobas SARS-CoV-2 assay. This study aimed to determine if thermal treatment significantly affects the qualitative detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the quantitative measurement of cobas SARS-CoV-2 ORF1a and E-gene target copy number using an in-house quantitative method. A collection of positive (n = 238) and negative samples (n = 196) was tested in parallel comparing thermal treatment (75 °C for 15 minutes) to room-temperature. There were no significant differences in the final qualitative outcomes for thermal treatment versus room-temperature (99.8% agreement) despite a statistically significant reduction (P < 0.05) in target copy number following thermal treatment. The median ORF1a and E-gene reduction in target copy number was -0.07 (1.6%) and -0.22 (4.2%) log10 copies/mL respectively. The standard curves for both ORF1a and E-gene targets were highly linear (r2 = 0.99). Good correlation was observed for ORF1a (r2 = 0.96) and E-gene (r2 = 0.98) comparing thermal treatment to room-temperature control.
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Project description:Microbiome analysis of oropharyngeal and nasopharyngeal samples of SARS-CoV-2 infected patients
2021-02-06 | GSE166281 | GEO
Project description:Fast, accurate, and reliable diagnostic tests are critical for controlling the spread of the coronavirus disease 2019 (COVID-19) associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The current gold standard for testing is real-time PCR; however, during the current pandemic, supplies of testing kits and reagents have been limited. We report the validation of a rapid (30 minutes), user-friendly, and accurate microchip real-time PCR assay for detection of SARS-CoV-2 from nasopharyngeal swab RNA extracts. Microchips preloaded with COVID-19 primers and probes for the N gene accommodate 1.2-μL reaction volumes, lowering the required reagents by 10-fold compared with tube-based real-time PCR. We validated our assay using contrived reference samples and 21 clinical samples from patients in Canada, determining a limit of detection of 1 copy per reaction. The microchip real-time PCR provides a significantly lower resource alternative to the Centers for Disease Control and Prevention-approved real-time RT-PCR assays with comparable sensitivity, showing 100% positive and negative predictive agreement of clinical samples.
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Project description:BackgroundGargle samples have been proposed as a noninvasive method for detection of SARS-CoV-2 RNA. The clinical performance of gargle specimens diluted in Cobas® PCR Media and in Cobas® Omni Lysis Reagent was compared to oropharyngeal/nasopharyngeal swab (ONPS) for the detection of SARS-CoV-2 RNA.Study designParticipants were recruited prospectively in two COVID-19 screening clinics. In addition to the ONPS, participants gargled with 5 ml of natural spring water split in the laboratory as follows: 1 ml was added to 4.3 ml of polymerase chain reaction (PCR) media and 400 μl was added to 200 μl of lysis buffer. Testing was performed with the Cobas® SARS-CoV-2 test on the Cobas® 6800 or 8800 platforms.ResultsOverall, 134/647 (20.7%) participants were considered infected because the ONPS or at least one gargle test was positive. ONPS had, respectively, a sensitivity of 96.3% (95% confidence interval [CI]: 91.3-98.5); both gargle processing methods were slightly less but equally sensitive (90.3% [95% CI: 83.9-94.3]). When ONPS and gargle specimens were both positive, the mean cycle threshold (Ct ) was significantly higher for gargles, suggesting lower viral loads.ConclusionGargle specimens directly added in PCR Media provide a similar clinical sensitivity to chemical lysis, both having a slightly, not significantly, lower sensitivity to ONPS.
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Project description:Background and objectivePoint-of-care type molecular diagnostic tests have been used for detecting SARS-CoV-2, although their clinical utility with nasal samples has yet to be established. This study evaluated the clinical performance of the cobas Liat SARS-CoV-2 & Influenza A/B (Liat) assay in nasal samples.MethodsNasal and nasopharyngeal samples were collected and were tested using the Liat, the cobas 6800 system and the cobas SARS-CoV-2 & Influenza A/B (cobas), and a method developed by National Institute of Infectious Diseases, Japan (NIID).ResultsA total of 814 nasal samples were collected. The Liat assay was positive for SARS-CoV-2 in 113 (13.9%). The total, positive, and negative concordance rate between the Liat and cobas/NIID assays were 99.3%/98.4%, 99.1%/100%, and 99.3%/98.2%, respectively. Five samples were positive only using the Liat assay. Their Ct values ranged from 31.9 to 37.2. The Ct values of the Liat assay were significantly lower (p < 0.001) but were correlated (p < 0.001) with those of other molecular assays. In the participants who tested positive for SARS-CoV-2 on the Liat assay using nasopharyngeal samples, 88.2% of their nasal samples also tested positive using the Liat assay.ConclusionThe Liat assay showed high concordance with other molecular assays in nasal samples. Some discordance occurred in samples with Ct values > 30 on the Liat assay.
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Project description:BACKGROUND:The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) has prompted a need for mass testing to identify patients with viral infection. The high demand has created a global bottleneck in testing capacity, which prompted us to modify available resources to extract viral RNA and perform reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) to detect SARS-COV-2. OBJECTIVES:Report on the use of a DNA extraction kit, after modifications, to extract viral RNA that could then be detected using an FDA-approved SARS-COV-2 RT-qPCR assay. MATERIALS AND METHODS:Initially, automated RNA extraction was performed using a modified DNA kit on samples from control subjects, a bacteriophage, and an RNA virus. We then verified the automated extraction using the modified kit to detect in-lab propagated SARSCOV-2 titrations using an FDA approved commercial kit (S, N, and ORF1b genes) and an in-house primer-probe based assay (E, RdRp2 and RdRp4 genes). RESULTS:Automated RNA extraction on serial dilutions SARS-COV-2 achieved successful one-step RT-qPCR detection down to 60 copies using the commercial kit assay and less than 30 copies using the in-house primer-probe assay. Moreover, RT-qPCR detection was successful after automated RNA extraction using this modified protocol on 12 patient samples of SARS-COV-2 collected by nasopharyngeal swabs and stored in viral transport media. CONCLUSIONS:We demonstrated the capacity of a modified DNA extraction kit for automated viral RNA extraction and detection using a platform that is suitable for mass testing. LIMITATIONS:Small patient sample size. CONFLICT OF INTEREST:None.
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Project description:The COVID-19 pandemic caused by the new Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) continues to threaten public health and burden healthcare systems worldwide. Whole SARS-CoV-2 genome sequencing has become essential for epidemiological monitoring and identification of new variants, which could represent a risk of increased transmissibility, virulence, or resistance to vaccines or treatment. Different next-generation sequencing approaches are used in SARS-CoV-2 sequencing, although with different ability to provide whole genome coverage without gaps and to reliably detect new variants. In this study, we compared the performance of three target enrichment methods (two multiplex amplification methods and one hybridization capture) using nasopharyngeal swabs from infected individuals. We applied these target enrichment methods to the same set of nasopharyngeal samples (N = 93) in high-throughput mode. SARS-CoV-2 genome was obtained using short-read next-generation sequencing. We observed that each method has some advantages, such as high mapping rate (CleanPlex and COVIDSeq) or absence of systematic variant calling error (SureSelect) as well as their limitations such as suboptimal uniformity of coverage (CleanPlex), high cost (SureSelect) or supply shortages (COVIDSeq). Nevertheless, each of the three target enrichment kits tested in this study yielded acceptable results of whole SARS-CoV-2 genome sequencing and either of them can therefore be used in prospective programs of genomic surveillance of SARS-CoV-2. Genomic surveillance will be crucial to overcoming the ongoing pandemic of COVID-19, despite its successive waves and continually emerging variants.
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Project description:ObjectivesThe gold-standard COVID-19 diagnosis relies on detecting SARS-CoV-2 using RNA purification and one-step retrotranscription and quantitative PCR (RT-qPCR). Based on the urgent need for high-throughput screening, we tested the performance of three alternative, simple and affordable protocols to rapidly detect SARS-CoV-2, bypassing the long and tedious RNA extraction step and reducing the time to viral detection.MethodsWe evaluated three methods based on direct nasopharyngeal swab viral transmission medium (VTM) heating before the RT-qPCR: a) direct without additives; b) in a formamide-EDTA (FAE) buffer, c) in a RNAsnapTM buffer.ResultsAlthough with a delay in cycle threshold compared to the gold-standard, we found consistent results in nasopharyngeal swab samples that were subject to a direct 70°C incubation for 10 min.ConclusionsOur findings provide valuable options to overcome any supply chain issue and help to increase the throughput of diagnostic tests, thereby complementing standard diagnosis.
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