The development of a rapid, high-throughput neutralization assay using a SARS-CoV-2 reporter.

Many methods have been developed to measure the neutralizing capacity of antibodies to SARS-CoV-2. However, these methods are low throughput and can be difficult to quickly modify in response to emerging variants. Therefore, an experimental system for rapid and easy measurement of the neutralizing capacity of antibodies against various variants is needed. In this study, we developed an experimental system that can efficiently measure the neutralizing capacity of sera by using a GFP-carrying recombinant SARS-CoV-2 with spike proteins of multiple variants (B.1.1, BA.5, or XBB.1.5). For all 3 recombinant chimeric genomes generated, neutralizing antibody titers determined by measuring GFP fluorescence intensity correlated significantly with those calculated from viral RNA levels measured by RT-qPCR in the supernatant of infected cells. Furthermore, neutralizing antibody titers determined by visually assessing GFP fluorescence using microscopy were also significantly correlated with those determined by RT-qPCR. By using this high-throughput method, it is now possible to quickly and easily determine the neutralizing capacity of antibodies against SARS-CoV-2 variants.