Fast SARS-CoV-2 detection by RT-qPCR in preheated nasopharyngeal swab samples

Julia Alcoba-Florez; Rafaela Gonzalez-Montelongo; Antonio Inigo-Campos; Diego Garcia-Martinez de Artola; Helena Gil-Campesino; Laura Ciuffreda; Agustin Valenzuela-Fernandez; Carlos Flores

We ensured that the non-template control did not amplify in any of the protocols both for the SARS-CoV-2 or the ACTB. Similarly, the positive control for the E-gene amplification yielded positive results in the RT-qPCR experiments of the three alternative sample treatment protocols. The use of specific and highly sensitive probes for coronavirus E-gene amplification leads to optimal results, therefore, the rationale for the first tests design has been followed in our assays (Corman et al., 2020) . Of note, this envelope small membrane protein (E) is required to produce a structurally complete viral particle together with three other major structural proteins: the spike (S), the nucleocapsid (N) and the membrane (M) proteins (Mortola and Roy 2004; Masters 2006; Wang 2017) . All samples gave positive results for the internal human ACTB. Ct for the E-gene amplification in the standard RNA extractions indicated that two of the positive COVID-19 cases had low Ct (<20) while the other two had large values (Ct>28) ( Table 2) .