Development of an oral DNA vaccine against MG7-Ag of gastric cancer using attenuated salmonella typhimurium as carrier

Figure 1 Incorporation of the epitope gene into the pcDNA3. 1 fragment by PCR: A product of 620bp was amplified by the first PCR (a), and a fragment of 660bp was amplified by the second PCR (b).

Figure 2 Hind III digestion of the recombinant plasmid after subcloning the PCR product into pcDNA3. 1 (+) from the pUCm-T vector: A fragment of 660bp was released (c), which corresponded to the size of the carrier fragment.

Figure 3 Sequencing of PCR product (partial sequence): By PCR, the two epitopes were fused together and incorporated into a pcDNA3. 1 fragment. The amino acid sequence of KPHVHTKGGGS correspondeds to the sequence of MG7-Ag mimotope. AKFVAAWTLKAAZ corresponds to the sequence of universal Th epitope PADRE.

Figure 4 PCR identification of the pcDNA3. 1 (+)-MG7/PADRE plasmid harbored by the Salmonella typhimurium SL3261: By PCR, a fragment of 800bp was amplified (d), suggesting the existence of epitope genes and removal of carrier fragment.

Figure 5 Immunohistochemical staining of the Ehrlich ascites carcinoma cells (EAC): Positive signal was seen in the cytoplasm and membrane of the EAC cells (A). When stained with a negative control monoclonal antibody (anti-E-tag antibody), the EAC cells showed no positive staining (B).