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

Retrospective, residual nasopharyngeal specimens that previously tested positive or negative for respiratory syncytial virus (RSV) using the Cepheid GeneXpert Flu/RSV kit or the Fast Track Diagnostics Respiratory Pathogens 21 PCR (FTD-RESP21) were extracted with our new approach on a Hamilton STAR liquid handling robot with 8 CO-RE channels. In brief, we added 150 µl of buffer RLT to 150 µl of viral transport medium for inactivation of the virus. We precipitated the contained RNA using 300 µl of Ampure XP beads, performed an extensive wash and eluted the RNA in 20 µl. For comparison, the same samples were extracted using the IVD-labelled bioMérieux NucliSENS easyMAG automated extraction platform, using 200 µl of VTM and eluted in 40 µl. We used 5 µl of the eluates of both extraction methods in our in-house LDT-RSV RT-qPCR assay.