PLoS ONE (Jan 2022)

Multicenter international assessment of a SARS-CoV-2 RT-LAMP test for point of care clinical application

  • Suying Lu,
  • David Duplat,
  • Paula Benitez-Bolivar,
  • Cielo León,
  • Stephany D. Villota,
  • Eliana Veloz-Villavicencio,
  • Valentina Arévalo,
  • Katariina Jaenes,
  • Yuxiu Guo,
  • Seray Cicek,
  • Lucas Robinson,
  • Philippos Peidis,
  • Joel D. Pearson,
  • Jim Woodgett,
  • Tony Mazzulli,
  • Patricio Ponce,
  • Silvia Restrepo,
  • John M. González,
  • Adriana Bernal,
  • Marcela Guevara-Suarez,
  • Keith Pardee,
  • Varsovia E. Cevallos,
  • Camila González,
  • Rod Bremner

Journal volume & issue
Vol. 17, no. 5

Abstract

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Continued waves, new variants, and limited vaccine deployment mean that SARS-CoV-2 tests remain vital to constrain the coronavirus disease 2019 (COVID-19) pandemic. Affordable, point-of-care (PoC) tests allow rapid screening in non-medical settings. Reverse-transcription loop-mediated isothermal amplification (RT-LAMP) is an appealing approach. A crucial step is to optimize testing in low/medium resource settings. Here, we optimized RT-LAMP for SARS-CoV-2 and human β-actin, and tested clinical samples in multiple countries. “TTTT” linker primers did not improve performance, and while guanidine hydrochloride, betaine and/or Igepal-CA-630 enhanced detection of synthetic RNA, only the latter two improved direct assays on nasopharygeal samples. With extracted clinical RNA, a 20 min RT-LAMP assay was essentially as sensitive as RT-PCR. With raw Canadian nasopharygeal samples, sensitivity was 100% (95% CI: 67.6% - 100%) for those with RT-qPCR Ct values ≤ 25, and 80% (95% CI: 58.4% - 91.9%) for those with 25 < Ct ≤ 27.2. Highly infectious, high titer cases were also detected in Colombian and Ecuadorian labs. We further demonstrate the utility of replacing thermocyclers with a portable PoC device (FluoroPLUM). These combined PoC molecular and hardware tools may help to limit community transmission of SARS-CoV-2.