Investigation of the recovery efficiency of CeUF method through RT-qPCR quantification of inactivated SARS-CoV-2 in untreated wastewater

Wastewater-based disease monitoring is an early warning system and a surveillance tool for infectious disease outbreaks regarding pathogens with pandemic potential. This study aimed at investigating the recovery efficiency of centrifugal ultrafiltration (CeUF), which is one of the most-used virus concentration methods, for inactive severe acute respiratory syndrome coronavi-rus 2 (SARS-CoV-2) added to wastewater. Inactivated SARS-CoV-2 was inoculated into untreated wastewater at different concentrations (4 × 103, 8 × 103, 16 × 103, 24 × 103 and 32 × 103 gene copy/ µL) and concentrated through ultrafiltration with a disposable centrifugal filter device. Total nucleic acids in concentrated filtrates were extracted and isolated by an automated system. In isolates, total RNA was measured by a UV/VIS spectrophotometer, and the recovered virus was quanti-fied by RT-qPCR with two gene regions (N1 and N2). The recovery rates were between 11% and 17.8% (mean 15.1%, CV below 15%). While there were positive correlations among the inoculated virus, total RNA and recovered virus, there was no correlation and linearity between the recovery rates. Despite limited recovery rates, CeUF integrated with RT-qPCR quantification can be a valid assay for monitoring SARS-CoV-2 in wastewater, and an early warning system.