Evaluation of two rapid ultrafiltration-based methods for SARS-CoV-2 concentration from wastewater

Abstract

Quantitative measurements of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in raw wastewater have been implemented worldwide since the beginning of the pandemic. Recent efforts are being made to evaluate different viral concentration methodologies to overcome supplier shortages during lockdowns. A set of 22-wastewater samples seeded with murine hepatitis virus (MHV), a member of the Coronaviridae family, and the bacteriophage MS2, were used to characterize and compare two ultrafiltration-based methods: a centrifugal ultrafiltration device (Centricon® Plus-70) and the automated concentrating pipette CP-Select™. Based on the recovery efficiencies, significant differences were observed for MHV, with Centricon® Plus-70 (24%) being the most efficient method. Nevertheless, concentrations of naturally occurring SARS-CoV-2, Human adenoviruses and JC polyomaviruses in these samples did not result in significant differences between methods suggesting that testing naturally occurring viruses may complement the evaluation of viral concentration methodologies. Based on the virus adsorption to solids and the necessity of a pre-centrifugation step to remove larger particles and avoid clogging when using ultrafiltration methods, we assessed the percentage of viruses not quantified after ultrafiltration. Around 23% of the detected SARS-CoV-2 would be discarded during the debris removal step. The CP-Select™ provided the highest concentration factor (up to 333×) and the lowest LoD (6.19 × 103 GC/l) for MHV and proved to be fast, automatic, highly reproducible and suitable to work under BSL-2 measures. ; This work was partially funded by the projects PCI2019-103643, RTI2018-097346-B-I00, and AGL2017-86797-C2-1-R projects, all funded by the Spanish Ministry of Science, Innovation and Universities. S. Bofill-Mas is a Serra-Hunter fellow at the University of Barcelona. This study is performed with partial support from the Water Research Institute of the University of Barcelona. Graphical abstract was created with Biorender.com. ICRA authors acknowledge the support from the Economy and Knowledge Department of the Catalan Government through Consolidated Research Group (ICRA-ENV 2017 SGR 1124). ICRA is part of the CERCA program. We would like to thank Dr. Zammit for his critical revision of the manuscript. ; Peer reviewed