CTL induction by DNA vaccine with Toxoplasma gondii-HSP70 gene

- Antigen-specific CTL is induced by DNA vaccine with T. gondii-HSP 70 gene.
- Both CD8+ and CD4+ CTL specific for T. gondii-infected DC cell line are induced.
- Fas/Fas ligand cascade is dominantly involved in the cytolysis mechanism.
- CD8+ or CD4+ T cells are capable of inducing acute and chronic phase protection.
- CD8+ and CD4+ T cells would co-work for chronic phase protection.

Toxoplasma gondii-derived heat shock protein 70 (T.g.HSP70) is a tachyzoite-specific virulent molecule. The DNA vaccine with T.g.HSP70 gene targeting peripheral epidermal or dermal dendritic cells (DC) induces in vivo DC maturation and successive early Th1 polarization at the draining lymph nodes (dLN) of C57BL/6 mice. In the present study, induction of cytotoxic T lymphocytes (CTL) has been explored. The CTL specific for a syngeneic DC line, DC2.4, either transfected with T. g.HSP70 gene or pulsed with recombinant T. g.HSP70 are induced in the spleen of the vaccinated mice. This CTL lyses T. gondii-infected, but not uninfected, DC2.4. Both CD8+ and CD4+ CTL are induced by the vaccine, and Fas/Fas ligand-mediated cytolysis dominantly participates in their CTL activities. Adoptive transfer experiments reveal that the vaccine-induced CD8+ or CD4+ T cells possess a protective role for toxoplasmosis at both acute and chronic phases of infection.