Abstract：Porcine GM-CSF gene was amplified from porcine expression plasmid pGM-CSF by PCR. Fragment containing GM-CSF gene was subcloned into somatostatin eukaryotic expression plasmid pcS/2SS to construct fusion-expression plasmid (pGM-CSF/SS) harboring porcine GM-CSF and somatostatin (SS). Restriction endonucleases digestion and DNA sequencing showed that the fusion-expression plasmid (pGM-CSF/SS) harboring porcine GM-CSF and somatostatin was successfully constructed. To study the immunization effect of pGM-CSF/SS on mice, a total of 30 mice at the age of 22 days were divided into 3 groups and immunized with salt solution (group 1), pcS/2SS (group 2) and pGM-CSF/SS (group 3), respectively. The results showed that lymphocyte proliferation response of pGM-CSF/SS was higher than that of the control group and pcS/2SS alone (P<0.05), indicating that GM-CSF could enhance lymphocyte proliferation responses. Fusion-expression plasmid of GM-CSF with SS significantly enhanced the P/N value of SS antibody compared to the control group and immunization of pcS/2SS alone. Percentage of mice with positive SS antibody immunized with pGM-CSF/SS was higher than that of other groups, which got to 60%. Percentage of that immunized with pcS/2SS was 30%. In conclusions, genetic adjuvant GM-CSF can enhance immune response of somatostatin DNA vaccine, which is an access to further research for immuno-enhancement of GM-CSF gene on somatostatin DNA vaccine.
