Construction and evaluation of the eukaryotic expression plasmid encoding two copies of somatostatin genes fused with hepatitis B surface antigen gene S.

The aim of current study was to evaluate the prospects of somatostatin DNA vaccine. Two copies of somatostatin (SS) genes were fused with the hepatitis B surface antigen (HBsAg) S gene using genetic engineering methods, the identified recombinant plasmid designated as pcS/2SS was transfected into HeLa cells to detect expression and antigenicity of target fusion protein, and its immunoreaction as well as safety was evaluated with animal experiments. The expressed target protein had a specific reaction with somatostatin antibody and showed a single strip result. A single injection of this vector stimulated long-term antigen-specific antibody responses in rats, and peak antibody levels occurred at the 2nd week of the initial injection. Additionally, the 50 microg immunized group resulted in a 13.5% increase in growth rate as compared with control group (111.7 g vs. 98.4 g). The genomic DNA was assayed for integrated plasmid using a sensitive PCR method, and the risk of mutation due to integration of pcS/2SS plasmid following intramuscular injection in mice was negligible. The successful construction of pcS/2SS DNA vaccine with good immunogenicity and safety has prospects to promote growth of animals.