University of Groningen, Department of Medical Microbiology, Molecular Virology Section, Groningen, The Netherlands

Correspondence to: T Daemen, University of Groningen, Department of Medical Microbiology, Molecular Virology Section, Ant Deusinglaan 1, 9713 AV Groningen, The Netherlands

We are developing immunization strategies against cervical carcinoma and premalignant disease, based on the use of recombinant Semliki Forest virus (SFV) encoding the oncoproteins E6 and E7 from high-risk human papilloma viruses (HPV). Thus far, protein-based, as well as genetic immunization studies have demonstrated low to moderate cellular immune responses against E6 and E7. To improve these responses, we modified the structure and expression level of the E6 and E7 proteins produced by the SFV vector. Specifically, a construct was generated encoding a fusion protein of E6 and E7, while furthermore a translational enhancer was included (enhE6,7). Infection of cells with recombinant SFV-enhE6,7 resulted in the production of large amounts of the E6,7 fusion protein. The fusion protein was more stable than either one of the separate proteins. Immunization of mice with SFV-enhE6,7 resulted in strong, long-lasting HPV-specific cytotoxic T lymphocyte responses. Tumor challenge experiments in mice demonstrated that immunization with SFV-enhE6,7 resulted in prevention of tumor outgrowth and subsequent protection against tumor re-challenge.

Gene Therapy 2001 9, 85-94. DOI: 10.1038/sj/gt/3301627

human papillomavirus; Semliki Forest virus; E6; E7; fusion protein; CTL