Cytotoxic CD8(+) T cells are Particularly important to the development of protective immunity against the intracellular protozoan parasite, Trypanosoma cruzi, the etiological agent of Chagas disease We have developed a new effective strategy of genetic immunization by activating CD8(+) T cells through the ubiquitin-fusion degradation (UFD) pathway. We constructed expression plasmids encoding the amastigote surface protein-2 (ASP-2) of T cruzi To induce the UFD pathway, a chimeric gene encoding ubiquitin fused to ASP-2 (pUB-ASP-2) was constructed Mice immunized with pUB-ASP-2 presented lower parasitemia and longer survival period, compared with mice immunized with pASP-2 alone Depletion of CD8(+) T cells abolished protection against T cruzi in mice immunized with pUB-ASP-2 while depletion of CD4(+) T cells did not influence the effective immunity Mice deficient in LMP2 or LMP7, subunits of immunoproteasomes, were not able to develop protective immunity induced These results Suggest that ubiquitin-fused antigens expressed in antigen-presenting cells were effectively degraded via the UFD pathway, and subsequently activated CD8(+) T cells Consequently, immunization with pUB-ASP-2 was able to induce potent protective immunity against infection of T cruzi (C) 2010 Elsevier Inc All rights reserved.