A Two-Component DNA-Prime/Protein-Boost Vaccination Strategy for Eliciting Long-Term, Protective T Cell Immunity against Trypanosoma cruzi

Abstract

In this study, we evaluated the long-term efficacy of a two-component subunit vaccine against Trypanosoma cruzi infection. C57BL/6 mice were immunized with TcG2/TcG4 vaccine delivered by a DNA-prime/Protein-boost (D/P) approach and challenged with T. cruzi at 120 or 180 days post-vaccination (dpv). We examined whether vaccine-primed T cell immunity was capable of rapid expansion and intercepting the infecting T. cruzi. Our data showed that D/P vaccine elicited CD4+ (30-38%) and CD8+ (22-42%) T cells maintained an effector phenotype up to 180 dpv, and were capable of responding to antigenic stimulus or challenge infection by a rapid expansion (CD8>CD4) with type 1 cytokine (IFNγ+ and TFNα+) production and cytolytic T lymphocyte (CTL) activity. Subsequently, challenge infection at 120 or 180 dpv, resulted in 2-3-fold lower parasite burden in vaccinated mice than was noted in unvaccinated/infected mice. Co-delivery of IL-12- and GMCSF-encoding expression plasmids provided no significant benefits in enhancing the anti-parasite efficacy of the vaccine-induced T cell immunity. Booster immunization (bi) with recombinant TcG2/TcG4 proteins 3-months after primary vaccine enhanced the protective efficacy, evidenced by an enhanced expansion (1.2-2.8-fold increase) of parasite-specific, type 1 CD4+ and CD8+ T cells and a potent CTL response capable of providing significantly improved (3-4.5-fold) control of infecting T. cruzi. Further, CD8+T cells in vaccinated/bi mice were predominantly of central memory phenotype, and capable of responding to challenge infection 4-6-months post bi by a rapid expansion to a poly-functional effector phenotype, and providing a 1.5-2.3-fold reduction in tissue parasite replication. We conclude that the TcG2/TcG4 D/P vaccine provided long-term anti-T. cruzi T cell immunity, and bi would be an effective strategy to maintain or enhance the vaccine-induced protective immunity against T. cruzi infection and Chagas disease.

A therapeutic nanoparticle vaccine againstTrypanosoma cruziin a BALB/c mouse model of Chagas disease

“…56,57 This is the first reported study utilizing a nanoparticle delivery system approach in developing a therapeutic vaccine against Chagas disease. Our findings of parasite reduction, but not elimination, are similar to the majority of Chagas disease vaccine studies.…”

Developments in the management of Chagas cardiomyopathy

“…[76] In a recent study, it was demonstrated that TcG2 and TcG4 DNA prime/protein boost vaccine achieved long-term protection against T. cruzi infection and Chagas disease, suggesting the vaccine-induced effector T cells can be long-lived and provide protection from parasitic infection. This vaccine-induced immunity waned slightly after 6 months post booster immunization, but was still sufficient to provide twofold control of invading pathogens [77] that, according to mathematical modeling, is sufficient to break the parasite transmission cycle [78] and prevent disease progression. [79] Pertinent to the theme of this review, it is important to note that many of the studies discussed highlight the importance of a preventive or therapeutic vaccine to control T. cruzi infection by at least decreasing parasite burden, cardiac tissue inflammation and damage or increasing survival if not providing sterile immunity.…”

Gene Expression Profiling and Functional Characterization of Macrophages in Response to Circulatory Microparticles Produced during <b><i>Trypanosoma cruzi</i></b> Infection and Chagas Disease

“…T. cruzi (SylvioX10/4) and C2C12 cells (an immortalized, mouse-derived myoblast cell line) were purchased from American Type Culture Collection (ATCC, Manassas VA) and T. cruzi trypomastigotes (infective stage) were propagated in C2C12 cells . T. cruzi antigens TcG2 and TcG4 were used as vaccine candidates and have been described in detail previously [19, 20]. Mice (n = five per group per experiment, two experiments) were injected in the quadriceps muscle with TcG2 and TcG4 antigens that were delivered as DNA-prime/protein-boost vaccine [19, 20].…”

“…T. cruzi antigens TcG2 and TcG4 were used as vaccine candidates and have been described in detail previously [19, 20]. Mice (n = five per group per experiment, two experiments) were injected in the quadriceps muscle with TcG2 and TcG4 antigens that were delivered as DNA-prime/protein-boost vaccine [19, 20]. Two weeks after immunization, mice were challenged with T. cruzi trypomastigotes (10,000/mouse), and sacrificed at ~120 days post-infection (pi), corresponding to the chronic disease phase [19, 20].…”

“…Mice (n = five per group per experiment, two experiments) were injected in the quadriceps muscle with TcG2 and TcG4 antigens that were delivered as DNA-prime/protein-boost vaccine [19, 20]. Two weeks after immunization, mice were challenged with T. cruzi trypomastigotes (10,000/mouse), and sacrificed at ~120 days post-infection (pi), corresponding to the chronic disease phase [19, 20]. Plasma samples were subjected to isolation of circulating microparticles as is described below.…”