Fig. 1
From: Antibody engineering improves neutralization activity against K417 spike mutant SARS-CoV-2 variants
Screening for antibodies that bind to SARS-CoV-2 S protein RBD domain. A DNA electrophoresis (left panel) and SDS-PAGE (right panel) were performed to confirm the expression and purification of SARS-CoV-2 S RBD protein. B The binding of purified S RBD protein to CB6 and REGN10933 mAbs was examined by ELISA assay. C Sketch map of COVID-19 patients’ scFv phage display library construction and mAbs screening. Briefly, VH and VL genes amplified and cloned from COVID-19 patients’ PBMC were inserted into T7 bacteriophage vector and packaged into phage particles displaying the scFv on their surfaces. The phage library was mixed with RBD protein that binds to their cognate epitopes. Bounded phage were eluted by immunoprecipitation with protein A/G coated magnetic beads. Last, PCR amplification and Illumina sequencing from the DNA of the bound phage were performed to reveal the sequence of scFv. D The binding of screened six mAbs to RBD protein was examined by ELISA assay. S309 and CR3022 Abs were used as positive control. E Sensorgrams of the binding of R3P1-B6, R3P2-A2, R3P1-E4 and S309 mAbs to RBD protein. The Ab concentrations were used as indicated. F The KD values in (E)