Figure 1. Overview of method.

IA) Expi293F cells are transfected with EGFP- and spike-expression plasmids and incubated for two days at 37 °C. IB) Cells are washed and stained with anti-spike antibodies bearing human constant domains followed by detection with anti-human-Fc fluorescent antibody. IC) Cells are analyzed on a flow cytometer to assess anti-spike antibody binding by geometric mean fluorescence intensity (GMFI). IIA) 293T cells are grown, transfected with EGFP and spike-expressing plasmids, and incubated for 2 days at 37 °C. IIB) NK-92 cells are grown with recombinant human IL-2. IIC) Spike-expressing 293T cells are loaded with calcein-AM dye and then co-incubated with NK-92 cells and anti-spike antibodies at 37 °C. IID) After a 4 h co-incubation, the release of fluorescent calcein into the media from lysed target cells is measured using a plate reader. Created in BioRender. Wilen, R. (2024) BioRender.com/s02t921