ABSTRACT
Introduction and objective: Since 2020, little is known about neutralizing antibody (NAb) responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus emerging and causing COVID-19 in humans. Here, we established a plaque reduction neutralization test (PRNT) to use as a method for detecting functional NAbs to SARS-CoV-2. Material(s) and Method(s): Vero cells were used as target cells for infection with the new coronavirus and cytopathic effects were obviously exhibited. Result(s): The development of plaque reduction after neutralization of virus with diluted specific antiserum was assessed according to a dose-response effect and consistency of test results with pooled antibody serum, which illustrated the robustness and dynamic reduction of plaque. In addition, the PRNT was used for evaluating functional NAb responses in Thai patients after symptom onset. Conclusion(s): The PRNT can be a method for measuring antibodies against live SARS-CoV-2 and future studies will be planned to investigate functional NAb responses elicited by any COVID-19 vaccine and to evaluate long-term protection of Thai COVID-19 vaccination. Copyright © 2022, Faculty of Pharmaceutical Sciences, Chulalongkorn University. All rights reserved.