Immunization with Human Papillomavirus 16 L1+E2 Chimeric Capsomers Elicits Cellular Immune Response and Antitumor Activity in a Mouse Model

• Published in: Viral immunology Vol. 29; no. 5; p. 276
• Main Authors: López-Toledo, Gabriela, Schädlich, Lysann, Alonso-Castro, Ángel Josabad, Monroy-García, Alberto, García-Rocha, Rosario, Guido, Miriam C, Gissmann, Lutz, García-Carrancá, Alejandro
• Format: Journal Article
• Language: English
• Published: United States 01-06-2016
• Subjects: Animals; Antigens, Viral - chemistry; Antigens, Viral - immunology; Capsid Proteins - chemistry; Capsid Proteins - genetics; Capsid Proteins - immunology; Cytotoxicity, Immunologic; Disease Models, Animal; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - immunology; Epitope Mapping; Epitopes - chemistry; Epitopes - immunology; Escherichia coli - genetics; Escherichia coli - metabolism; Female; Gene Expression; Human papillomavirus 16 - growth & development; Human papillomavirus 16 - immunology; Humans; Mice; Mice, Inbred C57BL; Oncogene Proteins, Viral - chemistry; Oncogene Proteins, Viral - genetics; Oncogene Proteins, Viral - immunology; Papillomavirus Infections - drug therapy; Papillomavirus Infections - immunology; Papillomavirus Infections - prevention & control; Papillomavirus Infections - virology; Papillomavirus Vaccines - administration & dosage; Papillomavirus Vaccines - genetics; Papillomavirus Vaccines - immunology; Plasmids - chemistry; Plasmids - metabolism; Recombinant Fusion Proteins - administration & dosage; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - immunology; T-Lymphocytes, Cytotoxic - immunology; T-Lymphocytes, Cytotoxic - virology
• ISSN: 1557-8976
• DOI: 10.1089/vim.2015.0080

Development of cervical cancer is associated with persistent infections by high-risk human papillomavirus (HPV). Although current HPV L1-based prophylactic vaccines prevent infection, they do not help to eliminate prevalent infections or lesions. Our aims were (i) to generate a vaccine combining prophylactic and therapeutic properties by producing chimeric capsomers after fusion of the L1 protein to different fragments of E2 from HPV 16, and (ii) to evaluate their capacity to generate an antitumoral cellular response, while conserving L1 neutralizing epitopes. Chimeric proteins were produced in Escherichia coli and purified by glutathione S-transferase (GST)-affinity chromatography. Their structure was characterized using size exclusion chromatography, sucrose gradient centrifugation, electron microscopy, and anti-L1 enzyme-linked immunosorbent assay. All chimeric proteins form capsomers and heterogeneous aggregates. One, containing part of the carboxy-terminal domain of E2 and its hinge region (L1Δ+E2H/NC, aa 206-307), conserved the neutralizing epitope H16.V5. We then evaluated the capacity of this chimeric protein to induce a cytotoxic T-cell response against HPV 16 E2. In (51)Cr release cytotoxicity assays, splenocytes from C57BL/6 immunized mice recognized and lysed TC-1/E2 cells, which express and present endogenously processed E2 peptides. Moreover, this E2-specific cytotoxic response inhibited the growth of tumors of TC-1/E2 cells in mice. Finally, we identified an epitope (aa 292-301) of E2 involved in this cytotoxic response. We conclude that the L1Δ+E2H/NC chimeric protein produced in bacteria can be an effective and economically interesting candidate for a combined prophylactic and therapeutic vaccine that could help eliminating HPV16-positive low-grade cervical lesions and persistent viral infections, thus preventing the development of lesions and, at the same time, the establishment of new infections.