Human papillomavirus (HPV) vaccines have the potential to prevent cervical cancer by preventing HPV infection or treating premalignant disease. We previously showed that DNA vaccination with the cottontail rabbit papillomavirus (CRPV) E6 gene induced partial protection against CRPV challenge and that the vaccine's effects were greatly enhanced by priming with granulocyte-macrophage colony-stimulating factor (GM-CSF). In the present study, two additional strategies for augmenting the clinical efficacy of CRPV E6 vaccination were evaluated. The first was to fuse a ubiquitin monomer to the CRPV E6 protein to enhance antigen processing and presentation through the major histocompatibility complex class I pathway. Rabbits vaccinated with the wild-type E6 gene plus GM-CSF or with the ubiquitin-fused E6 gene formed significantly fewer papillomas than the controls. The papillomas also required a longer time to appear and grew more slowly. Finally, a significant proportion of the papillomas subsequently regressed. The ubiquitin-fused E6 vaccine was significantly more effective than the wild-type E6 vaccine plus GM-CSF priming. The second strategy was to vaccinate with multiple CRPV early genes to increase the breadth of the CRPV-specific response. DNA vaccines encoding the wild-type CRPV E1-E2, E6, or E7 protein were tested alone and in all possible combinations. All vaccines and combinations suppressed papilloma formation, slowed papilloma growth, and stimulated subsequent papilloma regression. Finally, the two strategies were merged and a combination DNA vaccine containing ubiquitin-fused versions of the CRPV E1, E2, and E7 genes was tested. This last vaccine prevented papilloma formation at all challenge sites in all rabbits, demonstrating complete protection.Cervical human papillomavirus (HPV) infection is an extremely common sexually transmitted disease that affects an estimated 15% of women in the United States (18). Persistent lesions can be treated, but available treatments do not necessarily prevent recurrence (from latently infected tissues) and reinfection (with the same or other HPV types). Cervical carcinogenesis is initiated by infection with high-risk types of HPV (3, 28, 39), the most common of which are HPV type 16 (HPV-16) and HPV-18. Worldwide, cervical cancer is the second or third most common cancer in women (23).Vaccination against HPV to prevent infection and to treat premalignant disease could substantially decrease morbidity and mortality from cervical cancer. The ideal HPV vaccine would not only prevent primary lesions from forming but also provide therapy for established lesions. While humoral antibodies can prevent infection, only cellular immune responses against the early (intracellular) papillomavirus proteins can mediate both functions, by providing the helper cell activities necessary for proliferation and differentiation of B cells and/or differentiation into cytotoxic T cells (CTLs) as well as by elaborating inhibitory cytokines, thereby participating in the responses that occur during ...

Persistent human papillomavirus (HPV)-associated benign and malignant lesions are a major cause of morbidity and mortality worldwide. Vaccination against HPV early proteins could provide an effective means of treating individuals with established infections. Recombinant vesicular stomatitis virus (VSV) vectors have been used previously to elicit strong humoral and cellular immune responses and develop prophylactic vaccines. We have shown that VSV vectors also can be used to elicit therapeutic immunity in the cottontail rabbit papillomavirus (CRPV)-rabbit model of high-risk HPV infection. In the present study, three new VSV vectors expressing the CRPV E1, E2, or E7 protein were produced and compared to the previously generated VSV-E6 vector for therapeutic efficacy. To determine whether vaccine efficacy could be augmented by simultaneous vaccination against two CRPV proteins, the four vaccines were delivered individually and in all possible pairings to rabbits 1 week after CRPV infection. Control rabbits received the recombinant wild-type VSV vector or medium only. Cumulative papilloma volumes were computed for analysis of the data. The analyses showed that VSV-based vaccination against the E1, E2, E6, or E7 protein significantly reduced papilloma volumes relative to those of the controls. Furthermore, VSV-based CRPV vaccination cured all of the papillomas in 5 of 30 rabbits. Of the individual vaccines, VSV-E7 was the most effective. The VSV-E7 vaccine alone was the most effective, as it reduced cumulative papilloma volumes by 96.9% overall, relative to those of the controls, and ultimately eliminated all of the disease in all of the vaccinees. Vaccine pairing was not, however, found to be beneficial, suggesting antigenic competition between the coexpressed CRPV proteins. These preclinical results, obtained in a physiologically relevant animal model of HPV infection, demonstrate that VSV vectors deserve serious consideration for further development as therapeutic antitumor vaccines.Human papillomavirus (HPV) infections induce benign proliferative epithelial lesions (papillomas) at cutaneous and mucosal sites. Persistent lesions cause widespread morbidity and, when they progress to cancer, mortality (reviewed in references 1, 2, 7, 13, and 23). The new HPV virus-like particle (VLP) vaccine elicits strong HPV type-specific neutralizing antibodies and protects against subsequent infection with the corresponding HPV types (12). However, since it is unlikely to be immunotherapeutic, additional HPV vaccines are needed to ameliorate the severity of disease in the millions of people already infected with HPV (reviewed in reference 37).A promising new approach to vaccine development uses attenuated recombinant vesicular stomatitis viruses (VSVs) as vaccines (reviewed in reference 26). Compared to other viral vectors, the VSV vector offers several advantages. It is replication competent, like the most effective human vaccines, but is not a human pathogen. It induces strong cell-mediated and humoral immune responses compara...