Rapid Detection of Novel Coronavirus (COVID-19) by Reverse Transcription-Loop-Mediated Isothermal Amplification

Laura E Lamb; Sarah N Bartolone; Elijah Ward; Michael B Chancellor

We sought to determine if this RT-LAMP assay worked in a range of different samples that might be collected in a clinical setting or as a possible non-invasive screening tool. This is important since it may not be feasible to collect serum from all patients, especially patients who are critically sick, dehydrated, the elderly, children, and neonates. Personnel trained in collecting blood specimens may also not be available, Furthermore, biological samples may contain chemicals that can inhibit nucleic acid assays if the sample is tested directly without first isolating the RNA. RT-LAMP worked in all the human sample types tested, and in samples from several individuals. We previously demonstrated that RT-LAMP for ZIKV does not require prior RNA isolation from the samples. 4, 5 Thus, we used unprocessed urine or serum samples in this study, which saves considerable time and reduced costs. In this RT-LAMP assay for COVID-19, the urine samples gave stronger RT-LAMP signals than the serum samples when spiked with identical amounts of COVID-19; however the amount of virus present in an infected individual will likely vary between different biological specimens and over the time course of the infection. Furthermore, we observed faint background banding by gel electrophoresis in oropharyngeal swabs, suggesting there may be some factor in this specimen that results in this. However, due to the specificity of the primers, we believe this does not interfere with correct interpretation of the RT-LAMP reaction, especially since the COVID-19 spiked sample can be correctly identified through color change and fluorescence . All rights reserved. No reuse allowed without permission. author/funder, who has granted medRxiv a license to display the preprint in perpetuity.