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

• Published in: Infection and Immunity 2009-10, Vol.77 (10), p.4383-4395
• Main Authors: de Alencar, Bruna C.G, Persechini, Pedro M, Haolla, Filipe A, de Oliveira, Gabriel, Silverio, Jaline C, Lannes-Vieira, Joseli, Machado, Alexandre V, Gazzinelli, Ricardo T, Bruna-Romero, Oscar, Rodrigues, Mauricio M
• Format: Article
• Language: English
• Subjects: Adenovirus; Animals; Biological and medical sciences; CD4-Positive T-Lymphocytes - immunology; CD8-Positive T-Lymphocytes - immunology; Chagas Disease - prevention & control; Female; Fundamental and applied biological sciences. Psychology; Immunization, Secondary - methods; Interferon-gamma - deficiency; Interferon-gamma - immunology; Life cycle. Host-agent relationship. Pathogenesis; Mice; Mice, Inbred C57BL; Microbial Immunity and Vaccines; Microbiology; Miscellaneous; Neuraminidase - genetics; Neuraminidase - immunology; Parasitemia - prevention & control; Pore Forming Cytotoxic Proteins - deficiency; Pore Forming Cytotoxic Proteins - immunology; Protozoa; Protozoan Vaccines - immunology; Survival Analysis; Trypanosoma cruzi; Trypanosoma cruzi - immunology; Vaccination - methods; Vaccines, DNA - immunology; Vaccines, Synthetic - immunology; Virology
• ISSN: 0019-9567; 1098-5522
• DOI: 10.1128/IAI.01459-08

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-γ) 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-γ or IFN-γ/tumor necrosis factor alpha) paralleled by a decreased expression of CD44 and KLRG-1. Our final goal was to determine the importance of IFN-γ in the presence of highly cytotoxic T cells. Vaccinated IFN-γ-deficient mice developed highly cytotoxic cells but failed to develop any protective immunity. Our study thus demonstrated a role for perforin and IFN-γ 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.