Broad-spectrum vaccine targeting cutaneous HPV

Mucosal high-risk (hr) human papillomaviruses (HPV) are causally associated with the development of all cervical and most anal cancers, and a fraction of other anogenital and oropharyngeal cancers, while low- risk (lr) HPV cause genital warts. Infections with common cutaneous HPV types cause common or plane skin warts. HPV types of genus Beta are hypothesized to be involved in the development of non- melanoma (,white) skin cancer (NMSC), the most common cancer in fair-skinned populations, which is steadily increasing in elderly and in immunosuppressed patients. Licensed HPV vaccines protect against the types causing the majority of cervical-, part of other anogenital- and oropharyngeal carcinomas, and most genital warts. However, they do not target HPV infections of the skin, which are of particular concern for immunosuppressed (e.g. organ transplant) patients at high risk to develop NMSC. A promising approach to expand the spectrum of protection of current mucosal HPV vaccines to cutaneous types is based upon the minor structural protein L2, which is capable to induce protection against a multiplicity of even distantly related heterologous HPV. This approach requires identification of sequences (epitopes) within the L2 protein that induce broad cross-neutralization of cutaneous types. This will be achieved by generating neutralizing monoclonal antibodies against the L2 protein of oncogenic Beta types HPV5 and HPV38. Identified epitopes will be validated and displayed repetitively on the surface of recombinant chimeric virus-like particles (VLP) to augment L2 peptide immunogenicity. VLP immunizations will be utilized to determine the vaccines capacity for cross-neutralization, and for cross-protection against challenge with heterologous HPV types in mouse models. Also, putative structural differences of mucosal and Beta type HPV capsids will be investigated that might influence induction of a protective immune response. Finally, chimeric VLP will be freeze-dried to increase their thermostability. If successful, omission of cold-chain requirements for storage and transport might facilitate vaccine distribution especially in developing countries.

Generation of a broad-spectrum vaccine candidate targeting cutaneous Beta human papillomaviruses (HPV) involved in skin cancer development Persistent infections of the mucosa with high-risk (hr) human papillomaviruses (HPV), most often HPV type 16, are causally associated with the development of all cervical and most anal cancers, and a fraction of other anogenital and oropharyngeal cancers, while low-risk (lr) HPV cause genital warts (condylomata). Infections with common cutaneous HPV types cause common or plane skin warts. Cutaneous HPV types of genus beta (beta-HPV) are hypothesized to be involved in the development of non-melanoma (,white') skin cancer (NMSC), the most common cancer in fair-skinned populations, which is steadily increasing in elderly and in immunosuppressed patients. Licensed multivalent (up to 9) HPV vaccines, which are based upon the major capsid protein L1 assembled to virus-like-particles (VLP), provide limited protection against the vaccine types causing the majority of cervical-, part of other anogenital- and oropharyngeal carcinomas, and most genital warts. However, they do not target HPV infections of the skin, which are of particular concern for immunosuppressed patients at high risk to develop NMSC. In this project we have generated four monoclonal antibodies (mAbs) directed against the minor structural protein L2 of several beta-HPV types. The mAbs showed broad cross-neutralization against a panel of tested beta types. Additionally, mAbs provided protection against experimental infection with several beta types HPV5/24/38. The amino acid sequences recognized by these mAbs (epitopes) were identified and peptide immunizations verified that they induce a cross-neutralizing antibody response. Epitopes were further used to develop 6 chimeric VLP that are based upon hrHPV16 L1-VLP and present the novel epitopes repetitively and closely spaced on the VLP surface. In mouse and rabbit immunizations, chimeric VLP induced broad neutralization against a large panel of tested beta types as well as HPV16. In passive serum transfers, a subset of chimeric VLP-raised sera protected mice against infection with beta types HPV24 and HPV5. All 6 chimeric VLP provided protection against HPV5 when mice were actively immunized. In conclusion, 4 mAbs were generated with broad cross-neutralizing and cross-protecting capacity to beta-HPV infection. Chimeric VLP-based vaccine candidates that present the novel L2 cross-neutralization epitopes induce a similar cross-neutralization profile and cross-protection in the infection mouse model. A broad-spectrum vaccine with efficacy against beta-HPV types may provide great benefit in particular for the increasing population of immunosuppressed patient e.g. organ transplant recipients at high risk to develop skin cancer.