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| Author(s): |
Ágtha de Alencar Muniz Chaves
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2012-12-17 |
| Examining board members: |
Paulo Lee Ho;
Armando Morais Ventura;
Luisa Lina Villa
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| Advisor: | Paulo Lee Ho |
| Abstract | |
Cervical cancer is one of the most important problems of public health, causing nearly 270 million deaths annually. Currently, cervical cancer is the second more common type in women worldwide and the highest incidences occuring in developing countries. Human papillomavirus (HPV) are the ethiologic agents of cervical cancer. HPV have a double-stranded circular DNA genome encoding eight viral proteins, E1, E2, E4, E5, E6, E7 (non-structural), and L1, L2 (structural), the last ones forming the viral capsid. L1 protein expressed in heterologous systems self-assembles into VLPs (\"Virus like Particles\"), the base of prophylactic vaccines available commercially, Gardasil and Cervarix. In this work, we produced VLPs of HPV-16 L1 protein in the methylotrophic yeast Pichia pastoris for purification assays. Initially, samples obtained from purification presented degradation and aggregation of L1 protein and also contaminants. The purification protocol was modified and samples obtained in the new process did not present degradation nor aggregation but the presence of some contaminants could still be detected. Therefore, samples obtained were semi-purified. A second approach to the development of an alternative vaccine was performed with the production of vaccine candidates based on the HPV L2 protein (HPV-16 L2, HPV-18 L2 and Multimeric L2) and we also expressed the same proteins fused to Staphyloccocus aureus ZZ domain, using it as an adjuvant. In general, the fused proteins induced low antibodies titer and low neutralizing antibodies titer when compared to other formulations. Neutralizing antibodies elicited against homologous and heterologous pseudovirus depended on the adjuvant used. In another approach, trying to enhance immunologic antigen efficiencies, an immunization assay was performed with a formulation containing L2 HPV- 16, L2 HPV-18 and Multimeric L2 and the properties of three adjuvants were assessed. The vaccine formulations adjuvanted with alum/MPLA and cellular Pertussis low vaccine induced the highest levels of L2-specific antibodies. In addition, the usage of adjuvants maintained the antibody levels in the long term. The immunogenicity of each antigen depends on the adjuvant combination used. (AU) | |