A human type 5 adenovirus-based Trypanosoma cruzi therapeutic vaccine re-programs immune response and reverses chronic cardiomyopathy

PLoS Pathog. 2015 Jan 24;11(1):e1004594. doi: 10.1371/journal.ppat.1004594. eCollection 2015 Jan.

Abstract

Chagas disease (CD), caused by the protozoan Trypanosoma cruzi, is a prototypical neglected tropical disease. Specific immunity promotes acute phase survival. Nevertheless, one-third of CD patients develop chronic chagasic cardiomyopathy (CCC) associated with parasite persistence and immunological unbalance. Currently, the therapeutic management of patients only mitigates CCC symptoms. Therefore, a vaccine arises as an alternative to stimulate protective immunity and thereby prevent, delay progression and even reverse CCC. We examined this hypothesis by vaccinating mice with replication-defective human Type 5 recombinant adenoviruses (rAd) carrying sequences of amastigote surface protein-2 (rAdASP2) and trans-sialidase (rAdTS) T. cruzi antigens. For prophylactic vaccination, naïve C57BL/6 mice were immunized with rAdASP2+rAdTS (rAdVax) using a homologous prime/boost protocol before challenge with the Colombian strain. For therapeutic vaccination, rAdVax administration was initiated at 120 days post-infection (dpi), when mice were afflicted by CCC. Mice were analyzed for electrical abnormalities, immune response and cardiac parasitism and tissue damage. Prophylactic immunization with rAdVax induced antibodies and H-2Kb-restricted cytotoxic and interferon (IFN)γ-producing CD8+ T-cells, reduced acute heart parasitism and electrical abnormalities in the chronic phase. Therapeutic vaccination increased survival and reduced electrical abnormalities after the prime (analysis at 160 dpi) and the boost (analysis at 180 and 230 dpi). Post-therapy mice exhibited less heart injury and electrical abnormalities compared with pre-therapy mice. rAdVax therapeutic vaccination preserved specific IFNγ-mediated immunity but reduced the response to polyclonal stimuli (anti-CD3 plus anti-CD28), CD107a+ CD8+ T-cell frequency and plasma nitric oxide (NO) levels. Moreover, therapeutic rAdVax reshaped immunity in the heart tissue as reduced the number of perforin+ cells, preserved the number of IFNγ+ cells, increased the expression of IFNγ mRNA but reduced inducible NO synthase mRNA. Vaccine-based immunostimulation with rAd might offer a rational alternative for re-programming the immune response to preserve and, moreover, recover tissue injury in Chagas' heart disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoviridae / genetics
  • Adenoviridae / immunology
  • Animals
  • CD8-Positive T-Lymphocytes / immunology
  • Chagas Cardiomyopathy / prevention & control*
  • Chagas Disease / immunology*
  • Chagas Disease / therapy*
  • Chronic Disease
  • Female
  • Immune System Phenomena
  • Mice
  • Mice, Inbred C57BL
  • Protozoan Vaccines / therapeutic use*
  • Trypanosoma cruzi / immunology*
  • Vaccination
  • Vaccines, DNA / genetics
  • Vaccines, DNA / immunology

Substances

  • Protozoan Vaccines
  • Vaccines, DNA

Grants and funding

This work was supported in part through grants from Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro/FAPERJ (APQ1-E-26/111.756/2008 and CNE/E-26/101.549/2010, E-26/110.153/2013, E-26/111.709/2013) and the Brazilian Research Council/CNPq (#474234/2012-6-Universal; #302534/2008-3; National Institute for Science and Technology for Vaccines – INCTV/DECIT/MS/CNPq; #403979/2012-9-DECIT/MS/CNPq). AVM, OBR, MMR, TG and JLV are CNPq research fellows. IRP is a research fellow from FAPERJ. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.