Immunization with cDNA Expressed by Amastigotes ofTrypanosoma cruziElicits Protective Immune Response against Experimental Infection

Open Access
Publisher Website
Google Scholar
Abstract
Immunization of mice with plasmids containingTrypanosoma cruzigenes induced specific antibodies, CD4+Th1 and CD8+Tc1 cells, and protective immunity against infection. In most cases, plasmids used for DNA vaccination contained genes encoding antigens expressed by trypomastigotes, the nonreplicative forms of the parasite. In this study, we explored the possibility of using genes expressed by amastigotes, the form of the parasite which replicates inside host cells, for experimental DNA vaccination. For that purpose, we selected a gene related to the amastigote surface protein 2 (ASP-2), an antigen recognized by antibodies and T cells from infected mice and humans, for our study. Using primers specific for theasp-2gene, four distinct groups of genes were amplified from cDNA from amastigotes of the Y strain ofT. cruzi. At the nucleotide level, they shared 82.3 to 89.9% identity with the previously describedasp-2gene. A gene namedclone 9presented the highest degree of identity with theasp-2gene and was selected for immunological studies. Polyclonal antisera raised against the C terminus of the recombinant protein expressed by theclone 9gene reacted with an antigen of approximately 83 kDa expressed in amastigotes ofT. cruzi. Immunization of BALB/c mice with eukaryotic expression plasmids containing theclone 9gene elicited specific antibodies and CD4+T-cell-dependent gamma interferon secretion. Upon challenge with trypomastigotes, mice immunized with plasmids harboring theclone 9gene displayed reduced parasitemia and survived lethal infection. We concluded that amastigote cDNA is an interesting source of antigens that can be used for immunological studies, as well as for vaccine development.

This publication has 56 references indexed in Scilit: