Publication date: Apr 01, 2025

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 (tCI), with establishment of a standard curve. In parallel, the improved Spearman and KcE4rber 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 log 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.

Semantics

Original Article