Benchmarking virus concentration methods for quantification of SARS-CoV-2 in raw wastewater

Wastewater-based epidemiology offers a cost-effective alternative to testing large populations for SARS-CoV-2 virus, and may potentially be used as an early warning system for SARS-CoV-2 pandemic spread. However, viruses are highly diluted in wastewater, and a validated method for their concentration and further processing, and suitable reference viruses, are the main needs to be established for reliable SARS-CoV-2 municipal wastewater detection. For this purpose, we collected wastewater from two European cities during the Covid-19 pandemic and evaluated the sensitivity of RT-qPCR detection of viral RNA after four concentration methods (two variants of ultrafiltration-based method and two adsorption and extraction-based methods). Further, we evaluated one external (bovine corona virus) and one internal (pepper mild mottle virus) reference virus. We found a consistently higher recovery of spiked virus using the modified ultrafiltration-based method. This method also had a significantly higher efficiency (p-value <0.01) for wastewater SARS-CoV-2 detection. The ultracentrifugation method was the only method that detected SARS-CoV-2 in the wastewater of both cities. The pepper mild mottle virus was found to function as a potentially suitable internal reference standard. (C) 2020 The Author(s). Published by Elsevier B.V.

Automated summary

Wastewater-based epidemiology provides a cost-effective approach for testing SARS-CoV-2 virus in large populations and can serve as an early warning system for pandemic spread. Efficient concentration methods and suitable reference viruses are essential for reliable detection in municipal wastewater. Studies show that the modified ultrafiltration-based method has higher recovery rates and efficiency for detecting SARS-CoV-2, with ultracentrifugation being the most effective method for detecting the virus in wastewater.