8H12, 3E2, and 1C4 were obtained by mouse hybridomas preparation as described previously (Tuekprakhon et al. 2022 (link)). Ascites of the three nAbs were prepared by injecting hybridoma cells into the peritoneal cavities of pristine-primed BALB/c mice and were collected 9–12 days later and stored at −20°C. In addition, the variable domain genes of S309 (Pinto et al. 2020 (link)), S2E12 (Tortorici et al. 2020 (link)), S2X35 (Starr et al. 2021 (link)), XMA01 (Wang et al. 2022d (link)), and VacW-209 (Ju et al. 2022 (link)) heavy and light chains were inserted into a pTT5 (Thermo Fisher Scientific) vector containing the constant region of the human IgG; and the recombinant antibodies were expressed in Expi293F cells through transient transfection. All murine (ascites) and recombinant mAbs were purified by affinity chromatography using MabSelect Sure resin (Cytiva) and were stored in PBS. To further prepare the Fab fragments, mAbs were digested with papain at 0.1% (w/w) in PBS containing 30 mmol/L l -cysteine and 50 mmol/L EDTA at 37°C for 12 h. Digestion was terminated with the addition of 20–30 mmol/L iodoacetamide. Fab fragments were then purified using protein A columns and dialyzed against PBS.
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