Enhanced the immunity activity of HPV16 DNA vaccine by the combination CpG oligonucleotides adjuvant cloned into plasmid backbone and IL-28B gene adjuvant

Therapeutic human papillomavirus (HPV) DNA vaccine is an attractive option to control existed HPV infection and related lesions. The two early viral oncoproteins, E6 and E7, are continuously expressed in most HPV-related pre- and cancerous cells, and are ideal targets for therapeutic vaccines. We have previously developed HPV 16 DNA vaccines encoding mE7/HSP70, which generated significant antitumor effects in mice. In this study, we utilized multiple strategies including the insertion of CpG oligonucleotides (ODNs) into the backbone of vaccine vector, selection of cytokine gene adjuvants, combination of mE6/HSP70 and mE7/HSP70, vaccination with electroporation, to further enhance the potency of HPV16 DNA vaccine, We found that combination of built-in CpG adjuvant and IL-28B gene adjuvant could induce higher CD8⁺T cell response in mice. Moreover the plasmids mE6/HSP70 combined with mE7/HSP70 could synergistically enhance the specific CD8⁺T cell response. Furthermore, vaccination with CpG-modified mE7/HSP70 and mE6/HSP70, plus IL-28B gene adjuvant, generated significantly preventive and therapeutic antitumor effect against HPV E6- and E7-expressing tumors in C57BL/6 mice. Our results suggested that it may be promising to effectively control HPV infection and associated diseases by combining these multiple strategies in HPV DNA vaccine.