Newswise — A new diagnostic test can detect the RNA of SARS-CoV-2, the virus that causes COVID-19, in urine, blood, saliva or mouth swab samples in just 30 to 45 minutes, according to a new study published June 12, 2020 in the open-access journal PLOS ONE by Laura Lamb of the Beaumont Health System, Michigan, USA, and colleagues.
SARS-CoV-2 is difficult to diagnose early in infection as patients may be asymptomatic or have mild, non-specific symptoms. The current standard for diagnostic molecular is quantitative reverse transcription PCR (qRT-PCR), which requires expensive equipment and trained personnel only available in limited laboratories. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) is a one-step technology with fewer barriers to use than qRT-PCR; reagents are inexpensive and can be stored at room temperature, the technique works with a range of sample types, and it has been found to be highly specific, sensitive, and fast for other infectious diseases.
In the new study, researchers developed an RT-LAMP diagnostic test for SARS-CoV-2 and measured the effectiveness of the test on blood, urine, saliva and mouth swab samples that had been spiked with different amounts of SARS-CoV-2 genetic material. The test was also used on clinical samples from COVID-19 patients.
The RT-LAMP test for SARS-CoV-2 successfully detected the virus in all human sample types that were spiked with SARS-CoV-2 genetic material,, within 30 to 45 minutes, with an estimated limit of detection of as few as 304 viral copies in a sample. Importantly, the test did not detect virus in samples spiked with RNA other coronaviruses, demonstrating specificity for SARS-CoV-2. In clinical mouth swab samples, RT-LAMP was positive for 95% (19/20) of samples positive by qRT-PCR and negative for 90% (18/20) of samples that were negative by qRT-PCR. The researchers note that those discrepancies between the methods could represent either false positives by the RT-LAMP, contamination or increased sensitivity of RT-LAMP compared to qRT-PCR. The current study was not powered to determine sensitivity in a clinical population.
Lamb summarizes: “This method can rapidly detect the virus for COVID-19 in clinical samples without expensive equipment.”
#####
Press-only preview: https://plos.io/2Uxhmr9
Image Caption: Detection of SARS-CoV-2 with RT-LAMP in patient nasopharyngeal swab samples with RNA isolation.
Image Credit: Lamb et al, 2020 (PLOS ONE, CC BY)
Citation: Lamb LE, Bartolone SN, Ward E, Chancellor MB (2020) Rapid detection of novel coronavirus/Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) by reverse transcription-loop-mediated isothermal amplification. PLoS ONE 15(6): e0234682. https://doi.org/10.1371/
Funding: This work was supported by the Maureen and Ronald Hirsch family philanthropic contribution. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
In your coverage please use this URL to provide access to the freely available article in PLOS ONE: https://journals.plos.org/
RSS