High-throughput extraction of SARS-CoV-2 RNA from nasopharyngeal swabs using solid-phase reverse immobilization beads

Mahesh K R Kalikiri; Mohammad Rubayet Hasan; Faheem Mirza; Thabisile Xaba; Patrick Tang; Stephan Lorenz

Today, most laboratories performing extraction of RNA from samples rely heavily on commercially available kits due to their ease of use and standardization across laboratories. When these kits become scarce, many laboratories will have to turn to alternative methods, but often lack the expertise or the resource to test and validate those alternative methods. The underlying principle of modern, paramagnetic bead-based isolation of nucleic acids is their precipitation from solution by a molecular crowding reagent such as polethylenglycol (PEG) under high salt conditions. It was first described for DNA 45 years ago (1) and later adapted to the isolation of viral RNA from tissues (2) . Modern iterations of this procedure such as Ampure XP add carboxyl-coated paramagnetic beads to the PEG solution, thus greatly accelerating the precipitation as well as alleviating the need for time-consuming centrifugations, enabling automation of this process on liquid handling robots (3). This method is highly efficient in recovering even minute amounts of nucleic acids from larger volumes, such as shown in the precipitation of single-cell genomes (4, 5) .