Protocol for monitoring of neutralizing antibodies to various receptor-binding domains using the tANCHOR system

Neutralizing antibody analysis against SARS-CoV-2 variants requires assays that rapidly adapt to protein mutations. Here, we present a protocol for monitoring neutralizing antibodies to various receptor-binding domains using the tANCHOR system. We describe steps for displaying variant receptor-binding domains on HeLa cells and producing tagged soluble angiotensin-converting enzyme 2 (ACE2). We then detail the procedures for establishing a cell-based ELISA to measure serum neutralization efficiency, using ACE2 competition as a readout. For complete details on the use and execution of this protocol, please refer to Ivanusic et al.¹.