ABSTRACT
As to date, more than 49 million confirmed cases of Coronavirus Disease 19 (COVID-19) have been reported worldwide. Current diagnostic protocols use qRT-PCR for viral RNA detection, which is expensive and requires sophisticated equipment, trained personnel and previous RNA extraction. For this reason, we need a faster, direct and more versatile detection method for better epidemiological management of the COVID-19 outbreak. In this work, we propose a direct method without RNA extraction, based on the Loop-mediated isothermal amplification (LAMP) and Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR associated protein (CRISPR-Cas12) technique that allows the fast detection of SARS-CoV-2 from patient samples with high sensitivity and specificity. We obtained a limit of detection of 16 copies/µL with high specificity and at an affordable cost. The diagnostic test readout can be done with a real-time PCR thermocycler or with the naked eye in a blue-light transilluminator. Our method has been evaluated on a small set of clinical samples with promising results.
ABSTRACT
The development of a quantitative-competitive reverse transcription-PCR (RT-PCR) assay to quantify dengue virus (DEN) genome (vRNA) and its replicative intermediate RNA (vRI) is described. A highly conserved region located on the DEN capsid-premembrane genes was used to produce a competitor RNA molecule which contains an internal deletion of 70 nucleotides. The competitor provides a suitable internal control useful to quantify viral RNA from all four dengue virus (DEN 1-4) serotypes. The detection limit of the assay was found to be 100 copies per reaction. This is a rapid, simple, sensitive, inexpensive and easy method for quantitation of DEN RNA species.