Fast SARS-CoV-2 detection by RT-qPCR in preheated nasopharyngeal swab samples
Julia Alcoba-Flórez, Rafaela González‐Montelongo, Antonio Íñigo-Campos, Diego García-Martínez de Artola, Helena Gil-Campesino, The Microbiology Technical Support Team, Laura Ciuffreda, Agustı́n Valenzuela-Fernández, Carlos Flores
Abstract
ObjectivesThe gold-standard COVID-19 diagnosis relies on detecting SARS-CoV-2 using RNA purification and one-step retrotranscription and quantitative PCR (RT-qPCR). Based on the urgent need for high-throughput screening, we tested the performance of three alternative, simple and affordable protocols to rapidly detect SARS-CoV-2, bypassing the long and tedious RNA extraction step and reducing the time to viral detection.MethodsWe evaluated three methods based on direct nasopharyngeal swab viral transmission medium (VTM) heating before the RT-qPCR: a) direct without additives; b) in a formamide-EDTA (FAE) buffer, c) in a RNAsnapTM buffer.ResultsAlthough with a delay in cycle threshold compared to the gold-standard, we found consistent results in nasopharyngeal swab samples that were subject to a direct 70°C incubation for 10 min.ConclusionsOur findings provide valuable options to overcome any supply chain issue and help to increase the throughput of diagnostic tests, thereby complementing standard diagnosis.