Identification of recombinant SS DNA vaccines encoding different lengths somatostatin and empty vector vaccine by PCR. Lanes 1, 2 and 3, C500 (ptCS/2SS-28-asd), C500 (ptCS/2SS-14-asd) and C500 (pCpG-asd) recombinant DNA vaccines 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-28-FLAG (1086 bp), tPA-HBsAg-S-2SS-14-FLAG (1002 bp) and CpG (178 bp) fragment, respectively.