Chagas disease caused by the protozoan parasite Trypanosoma cruzi is considered an important health problem in South America. In the mammalian host, intra-cellular amastigotes forms of T. cruzi are target of the cell mediated immune response. IFN-gama producing CD4 and CD8 T cells recognize epitopes of amastigotes and are important for the host resistance.Due to its capacity to activate IFN-gama producing CD4 and CD8 T cells, DNA vaccines are particularly interesting as a tool to generate a vaccine against Chagas disease. In the last few years, several publications showed that this type of immunization is successful in experimental infection. In our laboratory, we demonstrated that immunization with the amastigote surface protein 2 gene (ASP-2) generates IFN-gama producing CD4 and CD8 T cells and protective immunity against experimental T. cruzi infection in a highly susceptible mouse strain (A/Sn). Although interesting, our results suggest that new strategies should be developed to improve immunogenicity and consequently the protective immunity induced by the genetic vaccination using the asp-2 gene alone. The main goal of this projetct is the generation of new plasmids containing sequences encoding the central domain of ASP-2 or the CD8 T cell epitope (TEWETGQI) inserted into the gene of glycoprotein D (gD) of herpes simplex vírus. This strategy, described by Lasaro et al., 2005, aims the expression of this chimeric protein in the surface of host cells increasing its exposure to the host immune system. Three plasmids are being developed and our experimental procedure will consist in the genetic vaccination with the following plasmids: I) pRE only (control); II) pRE4-gD/P4-P7; III) pRE4-gD/P4-P5; IV) pRE4-gD/TEWETGQI; V) pIgSPclone9 (pcDNA3 containing the asp-2 gene). In immunized A/Sn mice, the cell mediated immune response will be evaluated by the IFN-gama (ELISPOT) using as target the peptide TEWETGQI. The protective immune response will be evaluated by the parasitemia and mortality and compared to the immune response induced by the asp-2 gene inserted into the pcDNA3 plasmid.
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