Study Of Chemotactic Antigen Gene Vaccine

DNA vaccine has been the focus of tumor vaccine study. However, the potential of DNA vaccine should be further improved. In this study, we synergistically used SLC and IgG Fc as the immunological adjuvants to enhance the potency of DNA vaccines. Using the HPV16 E7 as a model antigen and the pShuttle-CMV as the eukaryotic expressing vector, we constructed a chimeric plasmid DNA vaccine (named as pSLC-E7-Fc) by linking SLC to the N-terminal of E7 gene and linking Fc gene to the C-termianal of E7 gene. At the same time, we constructed the following six control plasmids: pE7-Fc, pSLC-E7, pE7, pSLC, pFc and pCMV.By RT-PCR and Western blotting, we confirmed that all plasmids including pSLC-E7-Fc could be efficiently expressed in the eukaryotic cells.Using the E7-positive C3 cells with good immunogenicity and TC-1 cells with bad immunogenicity as tumor models, we perfomed the tumor preventative and therapy experiments by gene gun immunization. Our results showed that in the C3 tumor therapy experiments (the initial tumor size being 6mmx6mm), tumor completely regressed in 100% of pSLC-E7-Fc-immunized mice, while in only 50% of pE7-Fc-immunized mice and 16% of pSLC-E7-immunized mice, and tumor progressively grew in all other control plasmids immunized mice; Furthermore, the tumor-eradicating mice remained tumor-free and other mice died.In TC-1 preventative experiments, 100% of mice receiving pSLC-E7-Fc remained tumor-free, whereas all the mice immunized with control DNA developed tumor. And no tumor grew after re-inoculation of a three-time dose of TC-1 cells to the opposite flank of the tumor-free mice. In the TC-1 metaphase tumor therapy experiments (the initial therapy beginning on day 15 after TC-1 inoculation), tumor completely regressed in 72% of pSLC-E7-Fc-immunized mice, while in only 28% of pE7-Fc-immunized mice and tumor progressively grew in all other control plasmids immunized mice. Furthermore, tumor-eradicating mice remained tumor-free and all other mice died.In the TC-1 terminal tumor therapy experiments (the initial therapy beginning on day 30 after TC-1 inoculation), vaccination with pSLC-E7-Fc greatly inhibited tumor growth...