title: Accuracy of chimeric proteins in the serological diagnosis of chronic chagas disease - a Phase II study.
abstract: The performance of current serologic tests for diagnosing chronic Chagas disease (CD) is highly variable. The search for new diagnostic markers has been a constant challenge for improving accuracy and reducing the number of inconclusive results.
  
  
  
  Here, four chimeric proteins (IBMP-8.1 to -8.4) comprising immunodominant regions of different Trypanosoma cruzi antigens were tested by enzyme-linked immunosorbent assay. The proteins were used to detect specific anti-T. cruzi antibodies in the sera of 857 chagasic and 689 non-chagasic individuals to evaluate their accuracy for chronic CD diagnosis. The antigens were recombinantly expressed in Escherichia coli and purified by chromatographic methods. The sensitivity and specificity values ranged from 94.3% to 99.3% and 99.4% to 100%, respectively. The diagnostic odds ratio (DOR) values were 6,462 for IBMP-8.1, 3,807 for IBMP-8.2, 32,095 for IBMP-8.3, and 283,714 for IBMP-8.4. These chimeric antigens presented DORs that were higher than the commercial test Pathozyme Chagas. The antigens IBMP-8.3 and -8.4 also showed DORs higher than the Gold ELISA Chagas test. Mixtures with equimolar concentrations were tested in order to improve the diagnosis accuracy of negative samples with high signal and positive samples with low signal. However, no gain in accuracy was observed relative to the individual antigens. A total of 1,079 additional sera were used to test cross-reactivity to unrelated diseases. The cross-reactivity rates ranged from 0.37% to 0.74% even for Leishmania spp., a pathogen showing relatively high genome sequence identity to T. cruzi. Imprecision analyses showed that IBMP chimeras are very stable and the results are highly reproducible.
  
  
  
  Our findings indicate that the IBMP-8.4 antigen can be safely used in serological tests for T. cruzi screening in blood banks and for chronic CD laboratory diagnosis.
authors.affiliation: Aggeu Magalhães Research Center, Oswaldo Cruz Foundation, Recife, Pernambuco, Brazil.|Chagas Disease Integrated Program, Oswaldo Cruz Foundation, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Fred Luciano Neves
authors.identifier: 0000-0002-3944-0818
authors.initials: FL
authors.lastname: Santos
authors.affiliation: Molecular Biology Institute of Paraná, Curitiba, Paraná, Brazil.
authors.forename: Paola Alejandra Fiorani
authors.initials: PA
authors.lastname: Celedon
authors.affiliation: Carlos Chagas Institute, Oswaldo Cruz Foundation, Curitiba, Paraná, Brazil.
authors.forename: Nilson Ivo Tonin
authors.initials: NI
authors.lastname: Zanchin
authors.affiliation: Aggeu Magalhães Research Center, Oswaldo Cruz Foundation, Recife, Pernambuco, Brazil.
authors.forename: Wayner Vieira
authors.initials: WV
authors.lastname: de Souza
authors.affiliation: Chagas Disease Integrated Program, Oswaldo Cruz Foundation, Rio de Janeiro, Rio de Janeiro, Brazil.|Biomanguinhos, Oswaldo Cruz Foundation, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Edimilson Domingos
authors.initials: ED
authors.lastname: da Silva
authors.affiliation: Molecular Biology Institute of Paraná, Curitiba, Paraná, Brazil.|Carlos Chagas Institute, Oswaldo Cruz Foundation, Curitiba, Paraná, Brazil.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Foti
authors.affiliation: Chagas Disease Integrated Program, Oswaldo Cruz Foundation, Rio de Janeiro, Rio de Janeiro, Brazil.|Molecular Biology Institute of Paraná, Curitiba, Paraná, Brazil.|Carlos Chagas Institute, Oswaldo Cruz Foundation, Curitiba, Paraná, Brazil.
authors.forename: Marco Aurélio
authors.initials: MA
authors.lastname: Krieger
authors.affiliation: Aggeu Magalhães Research Center, Oswaldo Cruz Foundation, Recife, Pernambuco, Brazil.|Chagas Disease Integrated Program, Oswaldo Cruz Foundation, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Yara de Miranda
authors.initials: YM
authors.lastname: Gomes
mesh_terms: D000569:Americas; D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D014355:Chagas Disease / Q000175:diagnosis*; D002845:Chromatography; D002908:Chronic Disease; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods*; D014349:Trypanosoma cruzi / Q000235:genetics / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D011994:Recombinant Proteins