[Construction, expression and immune response of eukaryotic plasmid secreting SNCG]

Hsc70-SNCG fusion protein cDNA fragment containing signal peptide sequence of Igkappa, MMP9, and P37 was inserted into the vector pVAX1 to construct recombinant plasmid pVAX-Igkappa-Hsc70-SNCG, pVAX-MMP9-Hsc70-SNCG, and pVAX-P37-Hsc70-SNCG. Three eukaryotic vectors were constructed and verified by restriction enzyme digestion and sequencing. After transfection with recombination plasmids in QM-7 cells, the transient expression and secretion of three fusion proteins were detected by ELISA and Western Blot. The results suggested that Hsc70-SNCG carrying three different signal peptides could be expressed and secreted by transfected cells, and three signal peptides effectively directed secretion of fusion protein by QM-7 cells. BALB/c mice were immunized by three plasmids using gene gun system. The serum levels of anti-SNCG antibodies in mice were measured by ELISA. The results showed that three secreted plasmids could stimulate humoral immune responses to SNCG in mice, which depended on the secreted expression levels induced by signal peptides.