LAUSR

Variable region sequences for light chain (LC) and heavy chain (HC) of cilgavimab and tixagevimab from literature (Dong et al., 2021) were synthesized by GENEWIZ and were genetically fused to a human kappa constant sequence of the LC and a human gamma IgG1 constant sequence of HC (Lai et al., 2010). LC and HC genes were then cloned into a bean yellow dwarf virus (BeYDV)-based geminiviral vector and transiently expressed in N. benthamiana plants by agroinfiltration as described previously (Chen and Lai, 2014). 7D11 mAb were extracted and purified according to published protocols (Jugler et al., 2020). Briefly, mAb-expressing N. benthamiana leaves 7 days post infiltration were harvested and homogenized in extraction buffer (1X phosphate-buffered saline, pH 5.2 with 10 mg/mL Na-L-ascorbate, 2mM phenylmethylsulfonyl fluoride, and 1mM ethylenediaminetetraacetic acid). The pH of the homogenate was adjusted to 5.2 and then centrifuged several times. The supernatant was filtered through a 0.2-micron vacuum filter. The clarified protein extract was subsequently subjected to Protein A (MabSelect, Cytiva) chromatography according to the manufacture’s protocol prior to further analysis.