Performance of the RT-LAMP-based eazyplex® SARS-CoV-2 as a novel rapid diagnostic test

•Detection of SARS-CoV-2 by eazyplex® RT-LAMP from swab samples in less than 30 min.•A higher limit of detection than that for conventional RT-PCR has to be considered.•Virus concentrations of 105 copies/mL were reproducibly detected.•No false-positive results were observed.•Suitability as a POC ass...

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Veröffentlicht in:Journal of clinical virology 2021-05, Vol.138, p.104817-104817, Article 104817
Hauptverfasser: Egerer, Renate, Edel, Birgit, Löffler, Bettina, Henke, Andreas, Rödel, Jürgen
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Sprache:eng
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Zusammenfassung:•Detection of SARS-CoV-2 by eazyplex® RT-LAMP from swab samples in less than 30 min.•A higher limit of detection than that for conventional RT-PCR has to be considered.•Virus concentrations of 105 copies/mL were reproducibly detected.•No false-positive results were observed.•Suitability as a POC assay to identify individuals with high viral loads. Diagnostic assays for severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2) that are easy to perform and produce fast results are essential for timely decision making regarding the isolation of contagious individuals. We evaluated the CE-approved eazyplex® SARS-CoV-2, a ready-to-use real time RT-LAMP assay for identification of the SARS-CoV-2 N and ORF8 genes from swabs in less than 30 min without RNA extraction. Oropharyngeal and nasal swabs from 100 positive and 50 negative patients were inoculated into 0.9 % saline and tested by NeuMoDx™ RT-PCR. An aliquot was diluted fivefold in Copan sputum liquefying (SL) solution and directly analyzed by eazyplex® SARS-CoV-2. In addition, 130 patient swabs were prospectively tested with both methods in parallel. Analytical sensitivity of the assay was determined using virus stock dilutions. Positive percent agreement (PPA) between the eazyplex® SARS-CoV-2 and RT-PCR was 74 % for samples with Ct values < 35. When using a Ct cut-off ≤ 28 the PPA increased to 97.4 %. In the prospective part of the study overall PPA of the eazyplex® kit was 66.7 % but increased to 100 % when only Ct values ≤ 28 were considered. There were no false positive results. The median time to positivity was 12.5 min for the N gene and 16.75 min for ORF8. Analytical sensitivity was 3.75 TCID50/mL. 105 virus copies/mL were reproducibly detected. The eazyplex® SARS-CoV-2 is a rapid assay that accurately identifies samples with high viral loads. It may be useful for near-patient testing outside of a molecular diagnostic laboratory.
ISSN:1386-6532
1873-5967
DOI:10.1016/j.jcv.2021.104817