Identification of recombinant plasmids ptCS/2SS-asd, ptS/2SS-asd and pCpG-asd by PCR. Lanes 1, 2 and 3, ptCS/2SS-asd, ptS/2SS-asd and pCpG-asd recombinant plasmids were amplified with T7 and BGH primers; Lane M, DL5000 DNA marker. Three bands shown in Lanes 1, 2 and 3 are tPA-CpG-HBsAg-S-2SS-FLAG (1002 bp), tPA-HBsAg-S-2SS-FLAG (975 bp) and CpG (178 bp) fragment, respectively.