Detection of anti-Trypanosoma cruzi antibodies by chimeric antigens in chronic Chagas disease-individuals from endemic South American countries

PLoS One. 2019 Apr 18;14(4):e0215623. doi: 10.1371/journal.pone.0215623. eCollection 2019.

Abstract

Background: Laboratory diagnosis of chronic Chagas disease is a troubling factor due to lack of reference tests. The WHO suggests the use of two distinct commercial serological tests in parallel. The performance of commercial immunoassays might fluctuate depending on the antigenic matrices and the local strains of T. cruzi in different geographical settings. The use of antigenic matrices based on chimeric proteins can solve these limitations. Here, we evaluated the diagnostic performance of two chimeric T. cruzi antigens (IBMP-8.1 and -8.4) to diagnose chronic Chagas disease in individuals from endemic South American countries.

Methodology/principal findings: IBMP-8.1 and IBMP-8.4 chimeric antigens were expressed as soluble proteins in E. coli and purified using chromatography methods. Reactivity of IBMP-8.1 and IBMP-8.4 was assessed using an in-house ELISA with sera from 122 non-infected and 215 T. cruzi-infected individuals from Argentina, Bolivia, and Paraguay. Cut-off values were based on ROC curves and performance parameters were determined using a dichotomous approach. Area under the curve values were > 99.7% for both IBMP-8.1 and IBMP-8.4 antigens. IgG levels in T. cruzi-positive and negative samples were higher for IBMP-8.4 than IBMP-8.1. Both IBMP-8.1 and -8.4 were 100% specific, while IBMP-8.4 were 100% sensitive compared to IBMP-8.1 (95.3%). Admitting RI values of 1.0 ± 0.10 as the inconclusive interval, 6.2% of the samples tested using IBMP-8.1 and 2.1% using IBMP-8.4 fell inside the grey zone. Based on accuracy and diagnostic odds ratio values, IBMP-8.4 presented the best performance. Differences in sensitivity and IgG levels among the samples from Argentina, Bolivia, and Paraguay were not significant.

Conclusions/significance: Our findings showed a notable performance of IBMP-8.1 and -8.4 chimeric antigens in diagnosing chronic Chagas disease in individuals from endemic South American countries, confirming our hypothesis that these antigens could be used in geographical areas where distinct T. cruzi DTUs occur.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Protozoan / blood*
  • Antigens, Protozoan / chemistry*
  • Chagas Disease / blood*
  • Chagas Disease / epidemiology
  • Chronic Disease
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Humans
  • Immunoglobulin G / blood*
  • Male
  • Recombinant Fusion Proteins / chemistry
  • South America / epidemiology
  • Trypanosoma cruzi*

Substances

  • Antibodies, Protozoan
  • Antigens, Protozoan
  • Immunoglobulin G
  • Recombinant Fusion Proteins

Grants and funding

This work was supported by: Fundación Bunge y Born 2012 Dr. Silvia Andrea Longhi; Consejo Nacional de Investigaciones Científicas y Tecnológicas PIP/0974-2011 Dr. Alejandro Gabriel Schijman; Gonçalo Moniz Institute PROEP/IGM 400904/2013-6 Dr. Mitermayer Galvão dos Reis; Coordination of Superior Level Staff Improvement CAPES - PROEX 0720/2018 Dr. Fred Luciano Neves Santos; National Council for Scientific and Technological Development CNPq Proc. No. 312195/2015-0 Dr. Nilson Ivo Tonin Zanchin; and National Council for Scientific and Technological Development CNPq Proc. No. 307319/2016-4 Dr. Mitermayer Galvão dos Reis. The funders were not involved in the design of the study, in the collection, analysis and interpretation of the data, or in writing the manuscript.