A GRA1 DNA Vaccine Primes Cytolytic CD8+ T Cells To Control Acute Toxoplasma gondii Infection

AUTOR(ES)

Scorza, T.

FONTE

American Society for Microbiology

RESUMO

Protective immunity against Toxoplasma gondii is known to be mediated mainly by T lymphocytes and gamma interferon (IFN-γ). The contribution of CD4+ and CD8+ T-lymphocyte subsets to protective immune responses against T. gondii infection, triggered by a GRA1 (p24) DNA vaccine, was assessed in this study. In vitro T-cell depletion experiments indicated that both CD4+ and CD8+ T-cell subsets produced IFN-γ upon restimulation with a T. gondii lysate. In addition, the GRA1 DNA vaccine elicited CD8+ T cells that were shown to have cytolytic activity against parasite-infected target cells and a GRA1-transfected cell line. C3H mice immunized with the GRA1 DNA vaccine showed 75 to 100% protection, while 0 to 25% of the mice immunized with the empty control vector survived challenge with T. gondii cysts. In vivo T-cell depletion experiments indicated that CD8+ T cells were essential for the survival of GRA1-vaccinated C3H mice during the acute phase of T. gondii infection, while depletion of CD4+ T cells led to an increase in brain cyst burden during the chronic phase of infection.

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