Designing of DNA Vaccine Based on a Secretory Form of Major Capsid Protein of Human Papillomavirus Type 18

More than 99% of cervical cancers are associated with human papillomaviruses (HPVs) worldwide. Current HPV vaccines are safe, highly immunogenic, with effective immunity against specific HPV types. However, DNA vaccines are a new appealing platform which can be considered for designing the HPV vaccines. This study aimed to construct a recombinant eukaryotic expression plasmid containing L1 of HPV-18, tissue plasminogen activators (𝑡PA), and pan HLA DRbinding epitope (PADRE) genes into the pVAX1 vector. The L1, 𝑡PA, and PADRE genes were amplified in a thermocycler. The polymerase chain reaction (PCR) products were cloned and insertion of the genes was confirmed using colony PCR, restriction enzymes analysis, and sequencing methods. Indirect immunofluorescence, RTPCR, and western blot assays were applied to identify the target gene in HEK-293 cells. Total I𝑔G and its isotypes in immunized mice were measured by enzymelinked immunosorbent assay technique. Western blot analysis showed a protein band of about 67.5 kDa in supernatant and cell lysate of transfected cells. The results of mice immunization with different constructs (group 1: the pVAXL1, group 2: pVAX-tPA-PADRE-L1, group 3: pVAX1, and group 4: PBS as controls) indicated that the pVAX1-tPA-PADRE-L1 construct induced a significantly higher level of total I𝑔G than pVAX1-L1 (p=0.003). In conclusion, pVAX1-tPA-PADRE-L1 recombinant plasmid is a highly immunogenicthe construct and suggests as a promising candidate for vaccine development against HPV type 18 in lowmiddleincome countries.