Figure 2.

Purification of recombinant protein antigens. Protein extracts of soluble and insoluble fractions from induced and non-induced cultures of recombinant E. coli strain T7 and the eluates obtained after IMAC were separated by SDS-PAGE (10% acrylamide) and stained by Coomassie Blue (A,B) or analysed by Western immunoblotting (C). (A) Identification of CD0873 in the soluble fraction, (B) Identification of CDTcdB-RBD in the insoluble fraction, (C) Western immunoblot of purified recombinant CD0873 and CDTcdB-RBD probed with anti-His tag antibody, anti-CD0873 antibody or anti-TcdB antibody and detected by the addition of the appropriate HRP-conjugated secondary antibody and TMB substrate. Lane M: Colour pre-stained protein standard. Bands of expected molecular weight of 36 kDa for CD0873 and 61 kDa for CDTcdB-RBD were detected as indicated by the red arrows.