Evaluation of viral concentration methods for SARS-CoV-2 recovery from wastewaters

Abstract

Wastewater-based epidemiology (WBE) is a useful tool that has the potential to act as a complementary ap-proach to monitor the presence of SARS-CoV-2 in the community and as an early alarm system for COVID-19 out-break. Many studies reported low concentrations of SARS-CoV-2 in sewage and also revealed the need formethodological validation for enveloped viruses concentration in wastewater. The aim of this study was to eval-uate different methodologies for the concentration of viruses in wastewaters and to select and improve an optionthat maximizes the recovery of SARS-CoV-2. A total of 11 concentration techniques based on different principleswere evaluated: adsorption-elution protocolswith negatively chargedmembranesfollowedbypolyethylenegly-col (PEG) precipitation (Methods 1–2), PEG precipitation (Methods 3–7), aluminum polychloride (PAC)floccu-lation (Method 8), ultrafiltration (Method 9), skim milkflocculation (Method 10) and adsorption-elution withnegatively charged membrane followed by ultrafiltration (Method 11). To evaluate the performance of theseconcentration techniques, feline calicivirus (FCV) was used as a process control in order to avoid the risk associ-ated with handling SARS-CoV-2. Two protocols, one based on PEG precipitation and the other on PACfloccula-tion, showed high efficiency for FCV recovery from wastewater (62.2% and 45.0%, respectively). These twomethods were then tested for the specific recovery of SARS-CoV-2. Both techniques could recover SARS-CoV-2from wastewater, PACflocculation showed a lower limit of detection (4.3 × 102GC/mL) than PEG precipitation (4.3 × 103GC/mL). This work provides a critical overview of current methods used for virus concentration inwastewaters and the analysis of sensitivity for the specific recovery of SARS-CoV-2 in sewage. The data obtainedhere highlights the viability of WBE for the surveillance of COVID-19 infections in the community.