Recombination plasmid carrying hcg and survivin combination IL-12 generates specific immune responses and anti-tumor effects in a murine breast carcinoma model

The effectiveness of DNA vaccination alone is limited, because it often generates only a weak cellular immune response; therefore, the complementary use of adjuvants may be required to improve vaccine potency and enhance its immune protective effects. The present study aimed to determine the effect of recombinant DNA vaccine-based human hcg and survivin on the development of breast carcinoma in mice and the potential immune mechanisms involved, as well as the adjuvanticity of IL-12. Recombinant plasmids pVAX1-hcg-survivin and pVAX1-IL-12 were constructed, and injected into female mice intramuscularly (i.m.) followed by an electric pulse. The humoral and cellular immune responses after immunization were examined by enzyme linked immunosorbent assay (ELISA) and enzyme-linked immunospot assay (ELISPOT), respectively. To evaluate the anti-tumor efficacy of the plasmids, a mouse model with an hcg-survivin-expressing tumor was designed. Mice vaccinated with the pVAX1-hcg-survivin combination pVAX1-IL-12 plasmid generated the strongest inhibition efficacy on the growth of tumors and prolonged mouse survival. These observations emphasize the potential of IL-12 as an adjuvant for DNA vaccines and of vaccines based on hcg and surviving fusion gene and IL-12 as a promising treatment for breast carcinoma.