Extraction-free RT-LAMP to detect SARS-CoV-2 is less sensitive but highly specific compared to standard RT-PCR in 101 samples.
J Clin Virol
; 136: 104764, 2021 03.
Article
in English
| MEDLINE | ID: covidwho-1207043
ABSTRACT
The current scale of public and private testing cannot be expected to meet the emerging need for higher levels of community-level and repeated screening of asymptomatic Canadians for SARS-CoV-2. Rapid point-of-care techniques are increasingly being offered to fill the gap in screening levels required to identify undiagnosed individuals with high viral loads. However, rapid, point-of-care tests often have lower sensitivity in practice. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) for SARS-CoV-2 has proven sensitive and specific and provides visual results in minutes. Using a commercially available kit for RT-LAMP and primer set targetting nucleocapsid (N), we tested a blinded set of 101 archived nasopharyngeal (NP) swab samples with known RT-PCR results. RT-LAMP reactions were incubated at 65 °C for 30 min, using heat-inactivated nasopharyngeal swab sample in viral transport medium, diluted tenfold in water, as input. RT-LAMP agreed with all RT-PCR defined negatives (N = 51), and all positives with cycle threshold (Ct) less than 20 (N = 24), 65% of positives with Ct between 20-30 (N = 17), and no positives with Ct greater than 30 (N = 9). RT-LAMP requires fewer and different core components, so may not compete directly with the mainline testing workflow, preserving precious central laboratory resources for those with the greatest need. Careful messaging must be provided when using less-sensitive tests, so that people are not falsely reassured by negative results, but this caveat must be weighed against the clear benefits of reliably identifying those with high levels of virus in prioritized samples at the point of care.
Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Reverse Transcriptase Polymerase Chain Reaction
/
Nucleic Acid Amplification Techniques
/
Molecular Diagnostic Techniques
/
Point-of-Care Testing
/
COVID-19 Testing
/
COVID-19
Type of study:
Diagnostic study
Limits:
Humans
Country/Region as subject:
North America
Language:
English
Journal:
J Clin Virol
Journal subject:
Virology
Year:
2021
Document Type:
Article
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