Journal of medical virology
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Observational Study
Evaluation of seven commercial RT-PCR kits for COVID-19 testing in pooled clinical specimens.
There are more than 350 real-time polymerase chain reaction (RT-PCR) coronavirus disease-2019 (COVID-19) testing kits commercially available but these kits have not been evaluated for pooled sample testing. Thus, this study was planned to compare and evaluate seven commercially available kits for pooled samples testing. Diagnostic accuracy of (1) TRUPCR SARS-CoV-2 Kit (Black Bio), (2) TaqPath RT-PCR COVID-19 Kit (Thermo Fisher Scientific), (3) Allplex 2019-nCOV Assay (Seegene), (4) Patho detect COVID-19 PCR kit (My Lab), (5) LabGun COVID-19 RT-PCR Kit (Lab Genomics, Korea), (6) Fosun COVID-19 RT-PCR detection kit (Fosun Ltd.), (7) Real-time Fluorescent RT-PCR kit for SARS CoV-2 (BGI) was evaluated on precharacterised 40 positive and 10 negative COVID-19 sample pools. ⋯ However, the Fosun kit, LabGun Kit, and Patho detect kit could detect only 90%, 85%, and 75% of weakly positive samples, respectively. We conclude that all seven commercially available RT-PCR kits included in this study can be used for routine molecular diagnosis of COVID-19. However, regarding performing pooled sample testing, it might be advisable to use those kits that performed best regarding positive identification in samples' pool, that is TRUPCR SARS-CoV-2 Kit, TaqPath RT-PCR COVID-19 Kit, Allplex 2019-nCOV Assay, and BGI Real-time RT-PCR kit for detecting SARS CoV-2.
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The global outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) urgently requires an effective vaccine for prevention. In this study, 66 epitopes containing pentapeptides of SARS-CoV-2 spike protein in the IEDB database were compared with the amino acid sequence of SARS-CoV-2 spike protein, and 66 potentially immune-related peptides of SARS-CoV-2 spike protein were obtained. Based on the single-nucleotide polymorphisms analysis of spike protein of 1218 SARS-CoV-2 isolates, 52 easily mutated sites were identified and used for vaccine epitope screening. ⋯ The results of vaccine candidate sequences screening suggested that sequences (without linker, with linker GGGSGGG, EAAAK, GPGPG, and KK, respectively) were the best. The proteins translated by these sequences were relatively stable, with a high antigenic index and good biological activity. Our study provided vaccine candidate epitopes and sequences for the research of the SARS-CoV-2 vaccine.
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This study assesses the clinical performance of three anti-SARS-CoV-2 assays, namely EUROIMMUN anti-SARS-CoV-2 nucleocapsid (IgG) ELISA, Elecsys anti-SARS-CoV-2 nucleocapsid (total antibodies) assay, and LIAISON anti-SARS-CoV-2 spike proteins S1 and S2 (IgG) assay. One hundred and thirty-seven coronavirus disease 2019 (COVID-19) samples from 96 reverse-transcription polymerase chain reaction confirmed patients were chosen to perform the sensitivity analysis. Non-SARS-CoV-2 sera (n = 141) with a potential cross-reaction to SARS-CoV-2 immunoassays were included in the specificity analysis. ⋯ However, Elecsys performed better in terms of specificity. All three anti-SARS-CoV-2 assays had equivalent sensitivities 14 days from symptom onset to diagnose past-COVID-19 infection. We also confirmed that anti-SARS-CoV-2 determination before Day 14 is of less clinical interest.
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Diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) cases is based on the count of real-time reverse transcription-plymerase chain reaction (RT-PCR) positive people. Viral load by real-time RT-PCR has been suggested as a biomarker of the SARS-CoV-2 infection. However, the association of viral load and severity of the disease is not yet resolved. ⋯ Cases between 10 and 49 years old mostly showed low and moderate viral load during the first 2 days postinfection (range, 0.03 to 17.24; -1.50 to 1.24). Patients over 60 years old have high viral load up to the second week after the onset of symptoms (range, 25.32-155.42; 1.40-2.19), indicating the longer presence of the virus in them. These findings suggest the viral load in nasopharyngeal swabs would help to monitor the SARS-CoV-2 infection in mild coronavirus disease 2019 cases.
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We aimed to evaluate the rates of false-positive test results of three rapid diagnostic tests (RDTs) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific immunoglobulin G (IgG) and IgM detection. Two serum panels from patients hospitalized in Paris, France, and from patients living in Bangui, Central African Republic, acquired before the 2019 COVID-19 outbreak, were tested by 3 CE IVD-labeled RDTs for SARS-CoV-2 serology (BIOSYNEX® COVID-19 BSS [IgG/IgM]; SIENNA™ COVID-19 IgG/IgM Rapid Test Cassette; NG-Test® IgG-IgM COVID-19). Detectable IgG or IgM reactivities could be observed in 31 (3.43%) of the 902 IgG and IgM bands of the 3 RDTs used with all pre-epidemic sera. The frequencies of IgG/IgM reactivities were similar for European (3.20%) and African (3.55%) sera. ⋯ The test NG-Test® IgG-IgM COVID-19 showed the highest rates of IgG or IgM reactivities (6.12% [18/294]), while the test BIOSYNEX® COVID-19 BSS (IgG/IgM) showed the lowest rate (1.36% [4/294]). Some combinations of 2 RDTs in series allowed decreasing significantly the risk of false-positive test results. Our observations point to the risk of false-positive reactivities when using currently available RDT for SARS-CoV-2 serological screening, especially for the IgM band, even if the test is CE IVD-labeled and approved by national health authorities, and provide the rational basis for confirmatory testing by another RDT in case of positive initial screening.