Fig. 1. Characterization of the recombinant RBD dimer. (A) Structure of the RBD dimer (red: amino acids contacting the ACE2 receptor upon binding, pink: RBM, blue: glycan chains, grey: RBD core). (B) SE-HPLC chromatograms of the RBD-d/RBD-m mixture and the purified antigens. (C) RBD-d and RBD-m in reducing and non-reducing SDS-PAGE. (D) Interaction of RBD-d and RBD-m with the ACE2 receptor expressed in Vero cells. (E) Recognition of RBD-d by eight convalescent sera from a Cuban panel.
