Characterization of human papillomavirus type 11‐specific immune responses in a preclinical model

Objectives/Hypothesis: Human papillomavirus (HPV) types 6 and 11 are associated with recurrent respiratory papillomatosis (RRP). Although a prophylactic vaccine has been developed that protects against HPV infection, a therapeutic vaccine is still needed for those patients infected with and/or suffering from persistent disease. Therefore, we developed a novel, therapeutic DNA vaccine targeting HPV‐11 and characterized the in vivo immunologic responses generated against HPV‐11 E6 and E7 after DNA vaccination in a preclinical model. Methods: We generated a DNA vaccine that encodes the HPV‐11 E6 and E7 genes in a pcDNA3 backbone plasmid. We then vaccinated C57BL/6 mice with the pcDNA3‐HPV11‐E6E7 DNA plasmid. Splenocytes were harvested from these vaccinated animals and were incubated with overlapping peptides spanning either the HPV‐11 E6 or E7 protein. The frequency of interferon‐γ–releasing CD8 + T cell responses was then analyzed by flow cytometry. Results: Vaccinated mice with the HPV11‐E6E7 DNA generated strong CD8 + T cell responses against the E6 aa44‐51 peptide. We determined that the epitope is presented by the MHC class I H2‐K b molecule. No significant E7 peptide‐specific T cell responses were observed. Conclusions: We developed a novel DNA vaccine that targets the E6 gene of HPV‐11. Characterization of the immunologic responses elicited by this DNA vaccine reveals that the E6 aa44‐51 peptide contains the most immunogenic region for the HPV‐11 viral type. Knowledge of this specific T cell epitope and generation of a RRP preclinical model will allow for the development and evaluation of novel vaccine strategies targeting the RRP patient population. Laryngoscope, 2010