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Infection and Immunity, August 1999, p. 3855-3863, Vol. 67, No. 8
Departmento de Microbiologia,
Received 17 December 1998/Returned for modification 5 March
1999/Accepted 5 May 1999
Immunization with a plasmid DNA containing the gene encoding the
catalytic domain of trans-sialidase (TS) elicits protective immune responses against experimental Trypanosoma cruzi
infection. As several studies provided strong evidence that during
infection CD4 Th1 and CD8 T cytotoxic type 1 (Tc1) cells are important
factors in host resistance, the present study was designed to evaluate which T-cell types were activated in DNA-vaccinated BALB/c mice. We
found that bulk cells from DNA-immunized mice had CD4 and CD8 T cells
that produced gamma interferon (IFN-
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Predominance of CD4 Th1 and CD8 Tc1 Cells Revealed by
Characterization of the Cellular Immune Response Generated by
Immunization with a DNA Vaccine Containing a Trypanosoma
cruzi Gene
) but not interleukin-4 (IL-4)
or IL-10. To characterize the TS-specific T cells at the clonal level,
we generated CD4 and CD8 clones. We obtained cytotoxic CD4 clones of
the Th1 type that secreted large amounts of IFN-
but not IL-4 or
IL-10. Unexpectedly, we obtained other CD4 clones with a Th2 phenotype,
secreting IL-4 and IL-10 but not IFN-
. All CD8 clones were cytotoxic
and produced IFN-
. IL-4 and IL-10 were not secreted by these cells.
Using synthetic peptides, we determined a CD8 epitope recognized by
several clones as being represented by amino acids IYNVGQVSI. The
antiparasitic activity of a CD4 Th1 and a CD8 Tc1 clone was assessed in
vitro. CD4 or CD8 T cells significantly inhibited T. cruzi
development in infected macrophages or fibroblasts, respectively. We
concluded that DNA vaccine efficiently generates potentially protective
CD4 Th1 and CD8 Tc1 cells specific for a T. cruzi antigen,
therefore reinforcing the possibility of using this strategy for
developing a preventive or therapeutic vaccine against Chagas' disease.
*
Corresponding author. Mailing address: UNIFESP
Escola
Paulista de Medicina, Rua Botucatu, 862, 6° andar, 04023-062, São Paulo, SP, Brazil. Phone and fax: (55) (11) 571-1095. E-mail: Rodriguesm.dmip{at}epm.br.
Infection and Immunity, August 1999, p. 3855-3863, Vol. 67, No. 8
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
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