An enhanced immune response against G250, induced by a heterologous DNA prime-protein boost vaccination, using polyethyleneimine as a DNA vaccine adjuvant

Abstract

Abstract. The heterologous DNA prime-protein boost vaccination approach has been widely applied as an immune treatment for carcinoma. However, inefficient delivery of DNA remains a major issue. In the present study, polyethyleneimine (PEI) was used as a DNA vector carrier to improve the transfection efficiency of the DNA vaccine and stimulate the humoral and cellular immunity against the renal carcinoma-associated antigen G250. A protein vaccine was included in the immunization strategy in order to produce a prime-boost effect. A DNA plasmid encoding an antigen G250 fragment was constructed and complexed with PEI. A protein vaccine against G250 was expressed in BL21 (DE3) Escherichia coli cells, by transformation with a pET28a(+)/C-G250 plasmid. The protein was purified using a nickel-nitriloacetic acid purification system. The in vitro transfection efficiency of the DNA vaccine was analyzed in HEK293 human endothelial kidney cells. The in vitro transfection efficiency in HEK293 cells was highest 48 h after transfection. Furthermore, mice were primed with 200 µg pVAX1/C-250 plasmid complexed with PEI, and boosted using 50 µg of purified C-G250 protein.In order to evaluate the immune response the antibody titer, splenocyte response, and interferon-γ levels from CD8+ T-cell splenocytes were analyzed using ELISA, lymphocyte proliferation or enzyme-linked immunosorbent spot assays. Firstly, the pVAX1/C-G250 plasmid was shown to be constructed successfully. As compared with the DNA group, the antibody titer, lymphocyte proliferation percentage, and cytokine production level induced by the DNA-PEI and DNA-PEI+C-G250 groups were significantly higher. Furthermore, the DNA-PEI+C-G250 group exhibited the strongest humoral and cellular response. Owing to the adjuvant effect of PEI, the pVAX1/C-G250-PEI prime plus C-G250 protein boost regimen could induce a strong immune response, and has been proved to be a potent vaccine candidate against renal cell carcinoma.

Dual-targeting vaccine of FGL1/CAIX exhibits potent anti-tumor activity by activating DC-mediated multi-functional CD8 T cell immunity

“… 23 , 24 Studies have reported that various vaccines based on CAIX antigen can effectively stimulate antigen-specific immune responses and inhibit the growth of renal cancer. 25 , 26 The preliminary results of our research group also confirm that CAIX vaccine with the help of the adjuvant can induce antigen-specific multi-functional CD8 T cell immune response and suppress the tumor growth of renal cancer. 27 These results indicate that the developed DNA vaccine based on CAIX antigen is an effective way to treat renal cancer.…”

Polyethylenimine-based micro/nanoparticles as vaccine adjuvants

“…Different types of PEI, antigens, constructed strategies and immune routes are chosen in constructing the PEI-based vaccines in vivo. Frequently researched diseases include AIDS, 24,[73][74][75][76] Listeria monocytogenes infection, 56,77 respiratory diseases, 54,78-80 B cell lymphoma, 38 herpes simplex virus attacks, 81 viral B hepatitis, 82 renal cell carcinoma, 83 melanoma 84 and others. 85 The PEI-based vaccines work through almost all the known immune routes, and usually mimic the pathogenesis of the diseases themselves.…”

Combining DNA Vaccine and AIM2 in H1 Nanoparticles Exert Anti-Renal Carcinoma Effects via Enhancing Tumor-Specific Multi-functional CD8+ T-cell Responses

“…Human renal carcinoma-specific antigen CAIX, composed of 459 amino acids, in which 38-414 amino acids constitute extracellular domain, was highly expressed in 90% of renal carcinoma tissues. CAIX expression was almost not detected in normal renal tissues or other normal tissues, and only a small amount of CAIX expression was detected in gastric mucosa and bile duct epithelial cells (12). CAIX shows apparent tumor specificity and could serve as an ideal target for immunotherapy of renal carcinoma (13).…”