Immune response to plasmid DNA encoding HPV16-L1 protein

Objective: To test the immunogenicity of recombinant plasmid DNA containing human papillomavirus type 16-L1 (HPV16-L1) coding sequence of mice. Methods: The HPV16-L1 encoding sequence was generated by polymerase chain reaction (PCR), and inserted into TA cloning vector PCR II, then cloned in the eukaryotic expression vector pcDNA3.1 with CMV promoter. The recombinant plasmid DNA pcDNA-L1 was transferred into Cos-7 cells and used to immunize BALB/c mice via muscular injection. The expression of HVP16-L1 in transferred cells was identified by immunospot and immunocytochemistry, which tested specific anti-HPV16-L1 antibody in the serum of immunized mice. Results: Using the immunospot technique, we found L1 protein expression in pcDNA-L1 transferred cells. The immunocytochemistry studies demonstrated that the L1 protein was located in nuclei. In immunized mice, specific anti-HPV16- L1 antibodies could be detected by immunospot and immunocytochemistry 28 days after the first immunization and last at least 41 days. Conclusions: We constructed HPV-16-L1 eukaryotic expressing plasmid whose DNA could induce immuno-humoral response in mice. This observation will be helpful in designing HPV16 prophylactic vaccine.