Highly Accurate Chimeric Proteins for the Serological Diagnosis of Chronic Chagas Disease: A Latent Class Analysis

Abstract

Abstract.The existence of an imperfect reference standard presents complications when evaluating the unbiased performance of novel diagnostic techniques. This is especially true in the absence of a gold standard, as is the case in chronic Chagas disease (CD) diagnosis. To circumvent this constraint, we elected to use latent class analysis (LCA). Previously, our group demonstrated the high performance of four Trypanosoma cruzi–chimeric proteins (Molecular Biology Institute of Paraná [IBMP]-8.1, -8.2, -8.3, and -8.4) for CD diagnosis using several distinct immunoassays. Although commercial tests had previously been established as a reference standard, the diagnostic performance of these chimeric antigens could present bias because these tests fail to produce 100% accurate results. Thus, we used LCA to assess the performance of these IBMP chimeric antigens in chronic CD diagnosis. Using the LCA model as a gold standard, sensitivity and specificity values ranged from 93.5% to 99.4% and 99.6% to 100%, respectively. The accuracy values were 96.2% for IBMP-8.2, approximately 98% for IBMP-8.1 and IBMP-8.3, and nearly 100% for IBMP-8.4. For IBMP-8.1 and IBMP-8.2, higher positive predictive values were associated with increases in hypothetical prevalence. Similarly, higher hypothetical prevalence resulted in lower negative predictive values for IBMP-8.1, IBMP-8.2, and IBMP-8.3. In addition, samples with serodiscordant results from commercial serological tests were analyzed using LCA. Molecular Biology Institute of Paraná -8.1 demonstrated potential for use in confirmatory testing with regard to samples with inconsistent results. Moreover, our findings further confirmed the remarkable performance of the IBMP-8.4 antigen to diagnose chronic CD in both endemic and non-endemic areas.

Development of a New Lateral Flow Assay Based on IBMP‐8.1 and IBMP‐8.4 Chimeric Antigens to Diagnose Chagas Disease

“…Taking in consideration the lack of agreeability between tests' performance in different areas, our group previously assessed the performance of four T. cruzi chimeric antigens in various platforms, such as ELISA and liquid microarray (LUMINEX) [ 15 , 16 – 18 ]. To expand our studies, we tested in 32 clinical samples from people of distinct geographical regions in this investigation.…”

“…Considering the predicaments herein set forth, our group recently expressed and purified four T. cruzi -chimeric proteins (IBMP-8.1, -8.2, -8.3, and -8.4) and assessed their diagnostic performance in the serologic diagnostic of CD under ELISA or liquid microarray format assays [ 15 – 18 ] in different endemic settings in several Latin American countries [ 19 ] and in their immigrants living in Barcelona/Spain [ 20 ]. Additionally, these chimeric proteins have shown a negligible cross-reactivity with both American cutaneous and visceral leishmaniasis, demonstrating their utility in regions where T. cruzi and Leishmania spp.…”

Performance of recombinant chimeric proteins in the serological diagnosis of Trypanosoma cruzi infection in dogs

“…So, a strategy to address these limitations can be proposed by adopting synthetic recombinant chimeric antigens, composed of conserved amino acid sequences of several antigenic T . cruzi proteins [21,23,35,36]. To the best of our knowledge, this is the first study using recombinant chimeric proteins to diagnose T .…”

“…Fig 1 illustrates the SDS-PAGE of the antigens after purification. Details about IBMP composition has been seen in previous studies of our group [18,19,23].…”

“…Multi-epitope recombinant proteins, composed of several antigenically distinct amino acid sequences, have been proposed to improve the diagnostic performance of human chronic CD diagnosis [18–23]. Four multi-epitope proteins, namely IBMP-8.1, IBMP-8.2, IBMP-8.3, and IBMP-8.4, have been expressed by our team and their diagnostic potential has previously been evaluated on several technical platforms to diagnose human CD [18–20].…”