Impedance-based method for the quantification of infectious SARS-CoV-2
2025
Fraisse, A. | Guillier, Laurent | Cordevant, Christophe | Le Poder, Sophie | Perelle, Sylvie | Martin-Latil, Sandra | Virus Entériques (VE) ; Laboratoire de sécurité des aliments, sites de Maisons-Alfort et de Boulogne-sur-Mer (LSAl) ; Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES)-Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES) | Direction de l'Evaluation des Risques (DER) ; Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES) | Direction de la Stratégie et des Programmes (DSP) ; Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES) | Virologie UMR1161 (VIRO) ; École nationale vétérinaire d'Alfort (ENVA)-Laboratoire de santé animale, sites de Maisons-Alfort et de Normandie ; Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES)-Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | This investigation received financial support from the World Health Organization (WHO), through a German fund provided to the WHO R&D Blueprint. The authors alone are responsible for the views expressed in this publication and they do not necessarily represent the views, decisions or policies of WHO.
International audience
Show more [+] Less [-]English. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiologic agent involved in the coronavirus disease 2019 (COVID-19) pandemic. The development of infectious titration methods is crucial to provide data for a better understanding of transmission routes, as well as to validate the efficacy of inactivation treatments. Nevertheless, the low-throughput analytical capacity of traditional methods may be a limiting factor for a large screening of samples. The aim of the study was to develop a Real-Time Cell Analysis (RTCA) assay based on the measurement of cell impedance to quantify infectious SARS-CoV-2. The kinetics of cell impedance showed a virus-specific Cell Index (CI) drop. This enabled the correlation between viral concentrations and time at which a 50 % drop in CI values was observed (tCI50), with establishment of a standard curve. In parallel, the improved Spearman and Kärber method was used to quantify infectious titer since the virus-induced CI drop is correlated to the Cytopathic Effect. The estimated uncertainty was respectively 0.57, 0.36, and 0.26 log10 with 4, 8, and 16 wells per dilution. Thus, the RTCA assay is a powerful tool with a greatly simplified workflow for effective risk assessment in the field of food and environmental virology.
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