OBJECTIVE: To investigate the specific cell-mediated immune efficacy of the an HPV16 prophylactic vaccine. METHODS: C57BL/6 mice were randomly divided into 3 groups: experimental group I (treated with pcDNA L1), control group II (treated with pcDNA3.1) and control group III (treated with PBS buffer). The mice were immunized three times during a three-week interval. Ten to fourteen days after the third inoculation, a footpad swelling test was used to detect delayed-type hypersensitivity (DTH) responses. Antigen-specific splenocyte proliferation assay and quantitation of IFN-gamma cells in splenocytes were performed by FACS assay. RESULTS: In the experimental group, splenocytes actively proliferated after stimulation with HPV16 VLP, and had developed a markedly larger amount of CD8(+) IFN-gamma(+) cells, which is an index for special CTL. Also, the footpad was significantly thickened upon inoculation with HPV16 VLP. CONCLUSION: Naked DNA vaccine of HPV16 L1 can induce specific cell-mediated immune responses in mice, which should be considered for evaluation of HPV16 DNA vaccine feasibility.
Recombinant plasmid pcDNA-L1 was constructed by inserting HPV16-L1 gene fragment into eukaryotic expression plasmid pcDNA3.1. pcDNA-L1 was transfected into mammalian cells Cos-7 and the expression of HPV16-L1 protein was testified by immunohistochemistry(IHC). Then the recombinant plasmid was directly injected into the quadriceps muscle of BALB/c mice. Antibodies against HPV16-L1 in the immunized mice were positively detected by immunodot and IHC at 28 and 41 days after the last immunization.
