scholarly journals Can Testing Predict SARS-CoV-2 Infectivity? The Potential for Certain Methods to be a Surrogate for Replication-Competent Virus

2021 ◽  
Author(s):  
Matthew J. Binnicker
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Viral Rna ◽  
Molecular Diagnostic ◽  
Public Health Agencies ◽  
Diagnostic Assays ◽  
Molecular Tests ◽  
Primary Means ◽  
Clinical Illness ◽  
Antigen Tests

Since the beginning of the COVID-19 pandemic, molecular methods (e.g., real-time PCR) have been the primary means of diagnosing the disease. It is now well-established that molecular tests can continue to detect SARS-CoV-2 genomic RNA for weeks or months following the resolution of clinical illness. This has prompted public health agencies to recommend a symptom and/or time-based strategy for discontinuation of isolation precautions, which for hospitalized patients, results in significant use of personal protective equipment. Due to the inability of current molecular diagnostic assays to differentiate between the presence of remnant viral RNA (i.e., non-infectious) and replication-competent (i.e., infectious) virus, there has been interest in determining whether laboratory tests can be used to predict an individual’s likelihood of transmitting the virus to others. This review will highlight what is currently known about the potential for existing assays, such as real-time PCR and antigen tests, to predict active viral infection. In addition, data on the performance of new methods, such as molecular tests targeting viral RNA intermediates (e.g., subgenomic RNA), will be discussed.

scholarly journals Comparative performance of SARS-CoV-2 real-time PCR diagnostic assays on samples from Lagos, Nigeria

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246637
Author(s):  
Chika Kingsley Onwuamah ◽  
Azuka Patrick Okwuraiwe ◽  
Olumuyiwa B. Salu ◽  
Joseph O. Shaibu ◽  
Nnaemeka Ndodo ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Positive Sample ◽  
Viral Rna ◽  
Nasopharyngeal Swab ◽  
Comparative Performance ◽  
Repeat Testing ◽  
Diagnostic Assays ◽  
One Step ◽  
Instructions For Use

A key element in containing the spread of the SARS-CoV-2 infection is quality diagnostics which is affected by several factors. We now report the comparative performance of five real-time diagnostic assays. Nasopharyngeal swab samples were obtained from persons seeking a diagnosis for SARS-CoV-2 infection in Lagos, Nigeria. The comparison was performed on the same negative, low, and high-positive sample set, with viral RNA extracted using the Qiagen Viral RNA Kit. All five assays are one-step reverse transcriptase real-time PCR assays. Testing was done according to each assay’s manufacturer instructions for use using real-time PCR platforms. 63 samples were tested using the five qPCR assays, comprising of 15 negative samples, 15 positive samples (Ct = 16–30; one Ct = 35), and 33 samples with Tib MolBiol E-gene Ct value ranging from 36–41. All assays detected all high positive samples correctly. Three assays correctly identified all negative samples while two assays each failed to correctly identify one different negative sample. The consistent detection of positive samples at different Ct/Cq values gives an indication of when to repeat testing and/or establish more stringent in-house cut-off value. The varied performance of different diagnostic assays, mostly with emergency use approvals, for a novel virus is expected. Comparative assays’ performance reported may guide laboratories to determine both their repeat testing Ct/Cq range and/or cut-off value.

scholarly journals Serology- and Blood-PCR-Based Screening for Schistosomiasis in Pregnant Women in Madagascar—A Cross-Sectional Study and Test Comparison Approach

Pathogens ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 722
Author(s):  
Tanja Hoffmann ◽  
Imke Carsjens ◽  
Raphaël Rakotozandrindrainy ◽  
Mirko Girmann ◽  
Njary Randriamampionona ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Real Time ◽  
Real Time Pcr ◽  
Disease Burden ◽  
Cross Sectional Study ◽  
Molecular Diagnostic ◽  
Sectional Study ◽  
Cross Sectional ◽  
Diagnostic Assays ◽  
Edta Plasma

This work was conducted as a cross sectional study to define the disease burden of schistosomiasis in pregnant Madagascan women and to evaluate serological and molecular diagnostic assays. A total of 1154 residual EDTA blood samples from pregnant Madagascan women were assessed. The nucleic acid extractions were subjected to in-house real-time PCRs specifically targeting S. mansoni complex, S. haematobium complex, and African Schistosoma spp. on genus level, while the EDTA plasma samples were analyzed using Schistosoma-specific IgG and IgM commercial ELISA and immunofluorescence assays. The analyses indicated an overall prevalence of schistosomiasis in Madagascan pregnant women of 40.4%, with only minor regional differences and differences between serology- and blood PCR-based surveillance. The S. mansoni specific real-time PCR showed superior sensitivity of 74% (specificity 80%) compared with the genus-specific real-time PCR (sensitivity 13%, specificity 100%) in blood. The laborious immunofluorescence (sensitivity IgM 49%, IgG 87%, specificity IgM 85%, IgG 96%) scored only slightly better than the automatable ELISA (sensitivity IgM 38%, IgG 88%, specificity IgM 78%, IgG 91%). Infections with S. mansoni were detected only. The high prevalence of schistosomiasis recorded here among pregnant women in Madagascar calls for actions in order to reduce the disease burden.

scholarly journals Persistence of SARS-CoV-2 Viral RNA in Nasopharyngeal Swabs after Death: An Observational Study

2021 ◽  
Vol 9 (4) ◽  
pp. 800
Author(s):  
Francesca Servadei ◽  
Silvestro Mauriello ◽  
Manuel Scimeca ◽  
Bartolo Caggiano ◽  
Marco Ciotti ◽  
...  
Keyword(s):  
Viral Load ◽  
Observational Study ◽  
Real Time ◽  
Real Time Pcr ◽  
Pcr Detection ◽  
Viral Rna ◽  
Clinical Documentation ◽  
Post Mortem ◽  
Medical Assistance ◽  
Time Points

The aim of this study was to investigate the persistence of SARS-CoV-2 in post-mortem swabs of subjects who died from SARS-CoV-2 infection. The presence of the virus was evaluated post-mortem from airways of 27 SARS-CoV-2 positive patients at three different time points (T1 2 h; T2 12 h; T3 24 h) by real-time PCR. Detection of antibodies to SARS-CoV-2 was performed by Maglumi 2019-nCoV IgM/IgG chemiluminescence assay. SARS-CoV-2 viral RNA was still detectable in 70.3% of cases within 2 h after death and in 66,6% of cases up to 24 h after death. Our data showed an increase of the viral load in 78,6% of positive individuals 24 h post-mortem (T3) in comparison to that evaluated 2 h after death (T1). Noteworthy, we detected a positive T3 post-mortem swab (24 h after death) from 4 subjects who were negative at T1 (2 h after death). The results of our study may have an important value in the management of deceased subjects not only with a suspected or confirmed diagnosis of SARS-CoV-2, but also for unspecified causes and in the absence of clinical documentation or medical assistance.

scholarly journals A Multiplex Two-Color Real-Time PCR Method for Quality-Controlled Molecular Diagnostic Testing of FFPE Samples

PLoS ONE ◽  
2014 ◽  
Vol 9 (2) ◽  
pp. e89395 ◽  
Author(s):  
Jiyoun Yeo ◽  
Erin L. Crawford ◽  
Thomas M. Blomquist ◽  
Lauren M. Stanoszek ◽  
Rachel E. Dannemiller ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Diagnostic Testing ◽  
Molecular Diagnostic ◽  
Molecular Diagnostic Testing ◽  
Ffpe Samples ◽  
Pcr Method

scholarly journals Variola Virus-Specific Diagnostic Assays: Characterization, Sensitivity, and Specificity

2015 ◽  
Vol 53 (4) ◽  
pp. 1406-1410 ◽  
Author(s):  
Ashley V. Kondas ◽  
Victoria A. Olson ◽  
Yu Li ◽  
Jason Abel ◽  
Miriam Laker ◽  
...  
Keyword(s):  
Public Health ◽  
Real Time ◽  
Sensitivity And Specificity ◽  
Real Time Pcr ◽  
Variola Virus ◽  
Public Health Response ◽  
Diagnostic Assays ◽  
Health Response ◽  
Pcr Assays

A public health response relies upon rapid and reliable confirmation of disease by diagnostic assays. Here, we detail the design and validation of two variola virus-specific real-time PCR assays, since previous assays cross-reacted with newly identified cowpox viruses. The assay specificity must continually be reassessed as other closely related viruses are identified.

Parasitological versus molecular diagnosis of strongyloidiasis in serial stool samples: how many?

2017 ◽  
Vol 92 (1) ◽  
pp. 12-16 ◽  
Author(s):  
E. Dacal ◽  
J.M. Saugar ◽  
T. Soler ◽  
J.M. Azcárate ◽  
M.S. Jiménez ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Correct Diagnosis ◽  
Molecular Techniques ◽  
Maximum Sensitivity ◽  
Molecular Diagnostic ◽  
Molecular Diagnostic Techniques ◽  
Molecular Technique ◽  
Asymptomatic Patients ◽  
Stool Samples

AbstractStrongyloidiasis is usually an asymptomatic disease in immunocompetent patients, caused by Strongyloides stercoralis. However, in immunocompromised patients it can produce a severe clinical profile. Therefore, a correct diagnosis is necessary in these cases and in those chronic asymptomatic patients. The low sensitivity of classical parasitological techniques requires the analysis of multiple serial stool samples. Molecular diagnostic techniques represent an improvement in the detection of the parasite. The objective of this study was to evaluate the minimum number of samples necessary to achieve maximum sensitivity by real-time polymerase chain reaction (PCR). A total of 116 stool samples from 39 patients were analysed by direct microscopic observation, agar culture, Harada–Mori and real-time PCR, in one, two, three and four or more consecutive samples. After two serial samples, 6 out of 39 patients were positive by parasitological and molecular techniques, while 16 of them were real-time PCR positive, and all the patients detected by parasitology were also detected by the molecular technique, reaching 100.00% sensitivity versus 83.00% when analysing a single sample. These data also reflect apparently low specificity (51.52%) and positive predictive value (PPV) (27.27 %) values, due to the high number of cases detected by real-time PCR and not by parasitological techniques. These cases were confirmed as true positives when analysing three, four or more samples from the same patient. In conclusion, the application of molecular techniques decreases the number of serial stool samples necessary to give a diagnosis with the maximum sensitivity.

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