Therapeutic BCG Vaccine(University of Texas Health Science Center At San Antonio)

To develop human papillomavirus (HPV) 16 DNA vaccine for the treatment of HPV16 infection and its related tumors.

HPV16 oncogene E7 was modified by combined approaches including insertion and replication of specific region of E7 gene, murine codon optimization, and point-mutation at transforming regions of the E7 protein. The resulting artificial gene, named as mE7, was obtained by gene synthesis. The mE7 gene was then genetically fused to murine CD40 ligand (CD40L) by overlapping PCR to form the mE7/CD40L fusion gene. The mE7/CD40L gene was inserted into pVR1012 plasmid and then immunized C57/BL6 mice intramuscularly. The E7-specific IFN-gamma-secreting CD8+ T cells were analyzed with EIISPOT, and E7-specific antibody was measured by indirect ELISA. FACS assays were performed to analyze the activation of E7-specific Th cells. Mice were vaccinated, followed by tumor challenged or challenged before immunization. Tumor growth was observed.

The mE7 DNA vaccine elicited an increased E7-specific antibody level (P < 0.01), E7-specific IFN-gamma-secreting CD8+ T (P < 0.01), and CD4+ T cells number (P < 0.05), compared with those of mice immunized with wE7 gene. Furthermore, the mE7/CD40L DNA vaccine elicited an increased number of E7-specific IFN-gamma secreting CD8+ T cell compared with that of mice immunized with mE7 gene (P < 0.01); however, no significant differences were found between mice immunized with the mE7 gene and mE7/CD40L fusion gene in the E7-specific antibody production and Th cell activation. In the preventive experiment, all mice received the mE7 or mE7/CD40L remained tumor-free 7 weeks after challenges with TC-1 tumor cells, while the wE7 group exhibited tumor growth within 2 weeks. In the therapeutic experiment, all the mice in the wE7 group exhibited tumor growth within 8 days, while among mice receiving the mE7 and mE7/CD40L, 30% and 45% of mice remained tumor-free after TC-1 challenge, respectively. HE staining of tumor tissues showed copious lymphocytes infiltration around tumor cells in mE7 and mE7/CD40L mice with regression of tumor growth.

The mE7 DNA vaccine increases the E7-specific humoral and cellular immune responses, and the fusion of CD40L to mE7 gene enhances the specific immune responses and anti-tumor effects against HPV16 E7-expressing murine tumors. mE7/CD40L may therefore be a suitable and promising target for HPV16 therapeutic vaccine.

To generate a candidate HPV16 vaccine for experimental and therapeutical use for cervical cancer.

The mutants of HPV16 early E6 and E7 genes were inserted into a vaccinia virus expression vector. A strain of recombinant vaccinia virus was constructed through homologous recombination.

Showed that the mutant E6 and E7 genes were located at TK gene region of vaccinia virus Tiantan strain in a head to head orientation under the control of early/late promoters, H6 and 7.5K respectively. Studies in mice indicated that VmE6E7 could elicit specific antibodies against E6 and E7, and retarded or prevented tumor development in a proportion of C57 BL/6 mice challenged by syngeneic HPV16E6 and E7 transformed tumor cells.

The success in constructing VmE6E7 provides a basis for the further development of HPV16 therapeutic vaccine.