Genome-wide screening and identification of new Trypanosoma cruzi antigens with potential application for chronic Chagas disease diagnosis

PLoS One. 2014 Sep 16;9(9):e106304. doi: 10.1371/journal.pone.0106304. eCollection 2014.

Abstract

The protozoan Trypanosoma cruzi is the etiologic agent of Chagas disease, an infection that afflicts approximately 8 million people in Latin America. Diagnosis of chronic Chagas disease is currently based on serological tests because this condition is usually characterized by high anti-T. cruzi IgG titers and low parasitemia. The antigens used in these assays may have low specificity due to cross reactivity with antigens from related parasite infections, such as leishmaniasis, and low sensitivity caused by the high polymorphism among T. cruzi strains. Therefore, the identification of new T. cruzi-specific antigens that are conserved among the various parasite discrete typing units (DTUs) is still required. In the present study, we have explored the hybrid nature of the T. cruzi CL Brener strain using a broad genome screening approach to select new T. cruzi antigens that are conserved among the different parasite DTUs and that are absent in other trypanosomatid species. Peptide arrays containing the conserved antigens with the highest epitope prediction scores were synthesized, and the reactivity of the peptides were tested by immunoblot using sera from C57BL/6 mice chronically infected with T. cruzi strains from the TcI, TcII or TcVI DTU. The two T. cruzi proteins that contained the most promising peptides were expressed as recombinant proteins and tested in ELISA experiments with sera from chagasic patients with distinct clinical manifestations: those infected with T. cruzi from different DTUs and those with cutaneous or visceral leishmaniasis. These proteins, named rTc_11623.20 and rTc_N_10421.310, exhibited 94.83 and 89.66% sensitivity, 98.2 and 94.6% specificity, respectively, and a pool of these 2 proteins exhibited 96.55% sensitivity and 98.18% specificity. This work led to the identification of two new antigens with great potential application in the diagnosis of chronic Chagas disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Protozoan / chemistry
  • Antigens, Protozoan / genetics*
  • Antigens, Protozoan / immunology*
  • Chagas Disease / diagnosis*
  • Chagas Disease / immunology
  • Chagas Disease / parasitology
  • Cross Reactions / immunology
  • Disease Models, Animal
  • Enzyme-Linked Immunosorbent Assay
  • Epitope Mapping
  • Epitopes, B-Lymphocyte / chemistry
  • Epitopes, B-Lymphocyte / immunology
  • Female
  • Humans
  • Mice
  • Mice, Inbred C57BL
  • Peptide Fragments / chemistry
  • Peptide Fragments / immunology
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / immunology
  • Reproducibility of Results
  • Trypanosoma cruzi / genetics*
  • Trypanosoma cruzi / immunology*

Substances

  • Antigens, Protozoan
  • Epitopes, B-Lymphocyte
  • Peptide Fragments
  • Recombinant Proteins

Grants and funding

Fundação de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Instituto Nacional de Ciência e Tecnologia de Vacinas (INCTV), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES). CCO, ML, RTF and DCB are CNPq research fellows. JLRC and DRSR received scholarships from CNPq and TAOM, RAL and DSL received scholarships from CAPES. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.