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| Author(s): |
Cátia Taniela Perciani
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI) |
| Defense date: | 2011-05-12 |
| Examining board members: |
Martha Massako Tanizaki;
Lucila Okuyama Fukasawa;
Rita de Cássia Ruiz
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| Advisor: | Martha Massako Tanizaki |
| Abstract | |
Streptococcus pneumoniae is the main cause of invasive infectious diseases. Unlike polysaccharide (PS) based vaccines, conjugate vaccines have shown to protect children less than 2 years old. However, regardless of the success in reducing pneumococcal disease, recent reports have shown an increase in the rate of disease caused by serotypes not included in licensed conjugate vaccines. In order to avoid serotype replacement, our project proposes to test a surface exposed pneumococcal protein as carrier. Pneumococcal Surface Protein A (PspA), a conserved protein among various serotypes, and highly immunogenic was chosen to take part in the conjugate together with the Polysaccharide Serotype B of Streptococcus pneumoniae (PS6B), a serotype of high incidence in Brazil. In this sense, studies involving different reactional conditions were aimed at stablishing a high yield conjugation protocol. Also, the influence of different spacer between carrier protein and polysaccharide were evaluated on immune response. The replacement of EDAC (1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride), usually used in the activation of protein carboxyl groups, to DMT-MM (4-[4,6-Dimethoxy-1,3,5-triazin-2-yl]-4-methylmorpholinium chloride), was able to significantly increase the reactional yield from less than 10% to approximately 50%. The protection of lysines groups of PspA with formaldehyde increased conjugation specificity, with subsequent increase in reactional yield. Modified PspA maintained the same secondary structure of native PspA (circular dichroism analyses - CD) as well as its immunogenicity (antibody titers, deposition of complement and opsonophaghocytic activity). Despite circular dichroism analyses have shown changes in PspA secondary structure, immunological tests proved that this alteration did not affect its ability in inducing a protective immune response. Anti-PspA and anti-PS6B responses proved to be dose dependent, although PS6B acted as a poor immunogenic antigen in mice. (AU) | |
| FAPESP's process: | 08/06907-0 - Antipneumococcal Conjugate Vaccine PS6B-PspA |
| Grantee: | Cátia Taniela Perciani |
| Support Opportunities: | Scholarships in Brazil - Master |