Perforin and Gamma Interferon Expression Are Required for CD4⁺and CD8⁺T-Cell-Dependent Protective Immunity against a Human Parasite,Trypanosoma cruzi, Elicited by Heterologous Plasmid DNA Prime-Recombinant Adenovirus 5 Boost Vaccination

Abstract

A heterologous prime-boost strategy using plasmid DNA, followed by replication-defective recombinant adenovirus 5, is being proposed as a powerful way to elicit CD4 ؉ and CD8 ؉ T-cell-mediated protective immunity against intracellular pathogens. We confirmed this concept and furthered existing research by providing evidence that the heterologous prime-boost regimen using the gene encoding amastigote surface protein 2 elicited CD4 ؉ and CD8 ؉ T-cell-mediated protective immunity (reduction of acute parasitemia and prolonged survival) against experimental infection with Trypanosoma cruzi. Protective immunity correlated with the presence of in vivo antigen-specific cytotoxic activity prior to challenge. Based on this, our second goal was to determine the outcome of infection after heterologous prime-boost immunization of perforin-deficient mice. These mice were highly susceptible to infection. A detailed analysis of the cell-mediated immune responses in immunized perforin-deficient mice showed an impaired gamma interferon (IFN-␥) secretion by immune spleen cells upon restimulation in vitro with soluble recombinant antigen. In spite of a normal numeric expansion, specific CD8 ؉ T cells presented several functional defects detected in vivo (cytotoxicity) and in vitro (simultaneous expression of CD107a/IFN-␥ or IFN-␥/tumor necrosis factor alpha) paralleled by a decreased expression of CD44 and KLRG-1. Our final goal was to determine the importance of IFN-␥ in the presence of highly cytotoxic T cells. Vaccinated IFN-␥-deficient mice developed highly cytotoxic cells but failed to develop any protective immunity. Our study thus demonstrated a role for perforin and IFN-␥ in a number of T-cell-mediated effector functions and in the antiparasitic immunity generated by a heterologous plasmid DNA prime-adenovirus boost vaccination strategy.

Heterologous Plasmid DNA Prime-Recombinant Human Adenovirus 5 Boost Vaccination Generates a Stable Pool of Protective Long-Lived CD8 + T Effector Memory Cells Specific for a Human Parasite, Trypanosoma cruzi

“…ϩ T-cell immune responses of these two mouse strains following heterologous prime-boost vaccination, we observed that both mice had similar numbers of splenic specific CD8 ϩ T cells (13). Nevertheless, the CD8 ϩ T cells of the susceptible perforin-deficient mice had functional defects detected by immunological assays performed in vivo and in vitro (13).…”

“…In earlier studies, we described that protective immunity against T. cruzi infection, as measured by reductions in peak parasitemia and delayed mouse mortality, could be achieved by heterologous plasmid DNA priming-recombinant adenovirus boosting vaccination (13). This protective immunity was long-lived.…”

“…Nevertheless, the CD8 ϩ T cells of the susceptible perforin-deficient mice had functional defects detected by immunological assays performed in vivo and in vitro (13).…”

“…Both T-cell types cooperated to provide the long-lived protective immunity induced by vaccination, as depletion of either CD4 ϩ or CD8 ϩ T cells abolished most of the protective immunity. In addition, perforin and gamma interferon (IFN-␥) were described as critical for the acquired immunity of vaccinated animals against experimental infection with T. cruzi (13). Vaccinated perforin-deficient or wild-type mice were susceptible or resistant to T. cruzi infection, respectively.…”

Desenvolvimento de uma estratégia vacinal dose-reforço heterológo baseada em linhagens recombinantes de <i>Bacillus subitilis</i> para o controle de <i>Spreptococcus mutans</i>.

“…A estratégia dose-reforço heteróloga, permite a combinação de diversas formas de apresentação do antígeno em um mesmo regime vacinal, (HU et al, 1992;LASARO et al, 2005;DE ALENCAR et al, 2009;RIGATO et al, 2011) Em trabalho realizado por Ciabattini e colaboradores (2004), um regime vacinal do tipo "prime-boost" heterólogo, cujo "prime" foi realizado com esporos de B. subtilis como veículo vacinal vivo, capaz de expressar o fragmento C da toxina tetânica por via de mucosa oral, e o "boost" consistia na administração do mesmo antígeno em sua forma purificada, por via parenteral (subcutânea) resultou em respostas imunológicas antígenos-específicas locais e sistêmicas compatíveis com o correlato de proteção previsto para esta toxina. Apesar de promissor, o regime "prime-boost" heterólogo ainda não foi explorado com antígenos recombinante da proteína P1 de S. mutans, e poderia ser uma boa alternativa para entrega dos antígenos por vias de mucosa em estratégias vacinais contra a cárie.…”