Figure 2: The expression and the purity of rRBD were confirmed by SDS-PAGE analysis (A) and Western blotting using toxin Bspecific monoclonal antibody. (B). Purity of rRBD is shown in panel. A: lanes 1 to 4 correspond to cell lysate before IPTG induction, cell lysate after IPTG induction, supernatant of IPTGinduced cell lyseis, and eluent of 500 mM imidazole, respectively. The first lane contains molecular markers.