Validation of RT-qPCR primers and probes for new and old variants of SARS-CoV-2 in a world scale

Abstract

Introduction: The demand for molecular diagnosis of pathogens has surged dramatically since the onset of the COVID-19 pandemic. In this context, different diagnostic tests have been developed to identify SARS-CoV-2 in patient samples. The emergence of new variants of SARS-CoV-2 raises questions about whether the molecular tests available for diagnosis continue to be effective in detecting the virus in biological samples. Objective: This study analyzed the viability of molecular targets directed to N, E and RdRp genes available against the new variants of SARS-CoV-2. Methodology: For this, we used bioinformatics tools to analyze SARS-CoV-2 genomic data of different variants deposited in GSAID and NCBI virus genomic databases to assess the accuracy of molecular tests available for the diagnosis of COVID-19. We also developed software for analyzing mutation frequencies in different molecular targets from the mutation database. Results: Mutation frequency analysis revealed a high rate of mutations in the N, E and RdRp genes and targets, although the target regions were more conserved. Only three SNPs were recurrent in the sequences of the variants identified in different continents and all in different targets. On the other hand, the registered mutations are not consistent and do not appear frequently in isolates of the same variant in all regions of the world. Conclusion: Our data suggest that the molecular targets designed for the first SARS-CoV-2 variants remain valid for the identification of new virus variants despite the large number of identified haplotypes. However, false negative test failures can be identified by using more than one molecular target for the same sample. Genomic regions that are under evolutive selective pressure should be avoided in the use of the diagnostic, once the emergence of new variants may affect the efficiency of molecular testing on a global scale.