tetano
Editor, Senior Moderator
J Clin Virol
. 2021 Apr 1;138:104817.
doi: 10.1016/j.jcv.2021.104817. Online ahead of print.
Performance of the RT-LAMP-based eazyplex? SARS-CoV-2 as a novel rapid diagnostic test
Renate Egerer[SUP] 1 [/SUP], Birgit Edel[SUP] 1 [/SUP], Bettina L?ffler[SUP] 1 [/SUP], Andreas Henke[SUP] 2 [/SUP], J?rgen R?del[SUP] 3 [/SUP]
Affiliations
Abstract
Background: 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.
Objective: 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.
Study design: 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.
Results: 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 TCID[SUB]50[/SUB]/mL. 10[SUP]5[/SUP] virus copies/mL were reproducibly detected.
Conclusion: 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.
Keywords: POC; RT-LAMP; Rapid diagnostic test; SARS-CoV-2; Without RNA extraction.
. 2021 Apr 1;138:104817.
doi: 10.1016/j.jcv.2021.104817. Online ahead of print.
Performance of the RT-LAMP-based eazyplex? SARS-CoV-2 as a novel rapid diagnostic test
Renate Egerer[SUP] 1 [/SUP], Birgit Edel[SUP] 1 [/SUP], Bettina L?ffler[SUP] 1 [/SUP], Andreas Henke[SUP] 2 [/SUP], J?rgen R?del[SUP] 3 [/SUP]
Affiliations
- PMID: 33836452
- PMCID: PMC8015392
- DOI: 10.1016/j.jcv.2021.104817
Abstract
Background: 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.
Objective: 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.
Study design: 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.
Results: 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 TCID[SUB]50[/SUB]/mL. 10[SUP]5[/SUP] virus copies/mL were reproducibly detected.
Conclusion: 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.
Keywords: POC; RT-LAMP; Rapid diagnostic test; SARS-CoV-2; Without RNA extraction.