The humoral and cellular immune responses induced by HPV18L1-E6/E7 DNA vaccines in mice

Objective: To construct eukaryotic expression vector of HPV18 L1- E6, E7 chimeric gene and examine the humoral and cellular immune responses induced by this DNA vaccines in mice. Methods: The C-terminal of major capsid protein L1 gene and mutant zinc finger domains of early E6/7 oncogenes in HPV18 were integrated and inserted into eukaryotic expression vector pVAX1 to generate vaccines pVAX1-L1E6Mxx, E7Mxx. CHO cells were transiently transfected with the individual construct. Target protein expressions in the lysate of the transfected cells were measured by ELISA and immunocytochemistry. After BALB/c mice were vaccinated with various recombinant plasmids(pVAX1-L1-E6M3 or pVAX1-L1-E7M3) and immunie adjuvants (pLXHDmB7-2 or LTB) through different administration routes (intramuscular or intranasal), the great cellular immune responses were produced as revealed by delayed-type hypersensitivity (DTH) and lymphocyte proliferation, and the expression of IL-4 and IFN-γ cells in CD4⁺ and CD8⁺ subpopulations. Results: The highly efficient expression of pVAX1-L1E6Mxx, E7Mxx vector in host eukaryotic cells were demonstrated both by ELISA and immunocytochemistry. The level of specific serum IgG against HPV in experiment groups mice was much higher than that of control group, and intranuscular immunization group had the highest antibody level. Intramuscular immunization groups were superior to intranasal immunization groups in DTH response, splenocyte proliferation and CD8 ⁺ IFN-γ⁺ cells number, but CD4⁺ IL ⁴ cell number was higher in intranasal immunization groups. The immunization groups using pLXHDmB7-2 as adjuvant were superior to other groups in immunoresponse. Conclusion: These DNA vaccines produce remarkable cellular and humoral immune responses in the mouse and may provide as prophylatic and therapeutic candidates for HPV induced cancer treatment.