Figure 4. Western blot analysis of rabbit immune serum against toxin A C-terminal domains expressed in 293T cells (both supernatant, S and cell lysate, L) from either (A) TcdA-C or (B) tPA-TcdA-C DNA vaccines. DNA vector pJW4303 was used as a negative control. Serum from one TcdA-C DNA immunized rabbit (at 1:500 dilution) was used as the detection antibody. (C) western blot analysis of antigen expression from TcdB-N DNA vaccine transfected 293T cells. Cells transfected with the empty vector were used as negative controls. Serum from one TcdB-N-immunized rabbit (at 1:500 dilution) was used as the detection antibody.