Recombinant SARS-COV-2 Spike RBD(B.1.1.529/Omicron) is produced by Expi293 cells expression system. The target protein is expressed with sequence (Arg319-Phe541(G339D, S371L, S373P, S375F, K417N, N440K, G446S, S477N, T478K, E484A, Q493R, G496S, Q498R, N5