Comparing in vivo bioluminescence imaging and the Multi-Cruzi immunoassay platform to develop improved Chagas disease diagnostic procedures and biomarkers for monitoring parasitological cure

BACKGROUND: Chagas disease is caused by the protozoan parasite Trypanosoma cruzi and is a serious public health problem throughout Latin America. With 6 million people infected, there is a major international effort to develop new drugs. In the chronic phase of the disease, the parasite burden is extremely low, infections are highly focal at a tissue/organ level, and bloodstream parasites are only intermittently detectable. As a result, clinical trials are constrained by difficulties associated with determining parasitological cure. Even highly sensitive PCR methodologies can be unreliable, with a tendency to produce "false-cure" readouts. Improved diagnostic techniques and biomarkers for cure are therefore an important medical need. METHODOLOGY/PRINCIPAL FINDINGS: Using an experimental mouse model, we have combined a multiplex assay system and highly sensitive bioluminescence imaging to evaluate serological procedures for diagnosis of T. cruzi infections and confirmation of parasitological cure. We identified a set of three antigens that in the context of the multiplex serology system, provide a rapid, reactive and highly accurate read-out of both acute and chronic T. cruzi infection. In addition, we describe specific antibody responses where down-regulation can be correlated with benznidazole-mediated parasite reduction and others where upregulation is associated with persistent infection. One specific antibody (IBAG39) highly correlated with the bioluminescence flux and represents a promising therapy monitoring biomarker in mice. CONCLUSIONS/SIGNIFICANCE: Robust, high-throughput methodologies for monitoring the efficacy of anti-T. cruzi drug treatment are urgently required. Using our experimental systems, we have identified markers of infection or parasite reduction that merit assessing in a clinical setting for the longitudinal monitoring of drug-treated patients

Target product profile for a test for the early assessment of treatment efficacy in Chagas disease patients: An expert consensus.

Six to 7 million people are estimated to be infected by Trypanosoma cruzi, the parasite causing Chagas disease. Thirty to 40% of them, i.e., 1.8 to 2.4 million people, will suffer cardiac disorders and/or digestive clinical manifestations if they are not treated early during the course of the infection [1, 2]. However, only a small fraction of patients are properly diagnosed and treated [3]. Current clinical guidelines recommend treating T. cruzi–infected people if they are asymptomatic or present early symptoms of the disease (Table 1) [4, 5]. Benznidazole (BNZ) and nifurtimox (NFX) are the first-line antiparasitic treatments currently available, both with long administration regimens (60 days) that can produce adverse side effects [6–8]. Despite the fact they are not 100% effective in patients with chronic disease [9–12], they are the only drugs currently registered, and the benefits of their administration have been confirmed in several clinical studies. Currently, clinical trials with new compounds, using alternative regimens that aim to maintain efficacy whilst reducing toxicity, are ongoing and could lead to new therapeutic opportunities and/or policy change

Serological reactivity against T. cruzi-derived antigens: Evaluation of their suitability for the assessment of response to treatment in chronic Chagas disease.

Chagas disease, caused by the protozoan Trypanosoma cruzi, affects more than 6 million people worldwide. Following a mostly asymptomatic acute phase, the disease progresses to a long-lasting chronic phase throughout which life-threatening disorders to the heart and/or gastrointestinal tract will manifest in about 30% of those chronically infected. During the chronic phase, the parasitemia is low and intermittent, while a high level of anti-T. cruzi antibodies persist for years. These two features hamper post-chemotherapeutic follow-up of patients with the tools available. The lack of biomarkers for timely assessment of therapeutic response discourages a greater use of the two available anti-parasitic drugs, and complicates the evaluation of new drugs in clinical trials. Herein, we investigated in a blinded case-control study the serological reactivity over time of a group of parasite-derived antigens to potentially address follow up of T. cruzi chronically infected subjects after treatment. We tested PFR2, KMP11, HSP70, 3973, F29 and the InfYnity multiplexed antigenic array, by means of serological assays on a multi-national retrospective collection of samples. Some of the antigens exhibited promising results, underscoring the need for further studies to determine their potential role as treatment response biomarkers.We thank Dr. A. Egui, Dr A. Fernández-Villegas and A. López-Barajas from IPBLNsingle bondCSIC (Granada, Spain), Carme Subirá from ISGlobal (Barcelona, Spain), and Suelene B. N. Tavares from Hospital das Clínicas (Goiás, Brazil) for their technical assistance. We also want to thank Dr. B. Carrilero from Hospital Virgen de la Arrixaca (Murcia, Spain), Dr. Dayse E.C. de Oliveira from Hospital das Clínicas (Goiás, Brazil), and Dr. Raúl Chadi from Hospital General de Agudos “Dr. I. Pirovano” for their clinical follow up of patients. ISGlobal authors thanks the support by the Departament d'Universitats i Recerca de la Generalitat de Catalunya, Spain (AGAUR; 2017SGR00924), funding by the Instituto de Salud Carlos III project PI18/01054 and RICET Network for Cooperative Research in Tropical Diseases (RD12/0018/0010) and FEDER, and the support to ISGlobal from the Spanish Ministry of Science Innovation and Universities through the “Centro de Excelencia Severo Ochoa 2019–2023″ Program (CEX2018–000806-S), and from the Generalitat de Catalunya through the CERCA Program. IPBLN work was financially supported by grants SAF2016–81003-R and SAF2016–80998-R from the Programa Estatal I + D + i (MINECO) and ISCIII RICET (RD16/0027/0005) and FEDER. MJP research is supported by the Ministry of Health, Government of Catalunya (PERIS 2016–2010 SLT008/18/00132). TAJ thanks the support of Conselho Nacional de Pesquisa e Desenvolvimento Tecnologico (CNPq/ 313011/2018–4) and Fundação Oswaldo Cruz/MS (25380.001603/2017–89). Authors also thank Drugs for Neglected Diseases initiative and Fundacion Mundo Sano for financial support. For this project, DNDi received financial support from the following donors: UK Aid, UK; Directorate-General for International Cooperation (DGIS), The Netherlands; Swiss Agency for Development and Cooperation (SDC), Switzerland; Médecins Sans Frontières (MSF), International. The donors had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Evaluation of INNO-LIA Syphilis Assay as a Confirmatory Test for Syphilis

We evaluated the sensitivity and specificity of a new confirmatory test for treponemal antibodies, INNO-LIA Syphilis (Innogenetics NV, Ghent, Belgium), on a large number of sera from a clinical laboratory. This multiparameter line immunoassay (LIA) uses recombinant and synthetic polypeptide antigens derived from Treponema pallidum proteins. In a single-blinded cross-sectional retrospective study, 289 seronegative sera, 219 seropositive sera, and 23 sera with an indeterminate serological status for syphilis were analyzed. All sera were tested by the T. pallidum hemagglutination assay (TPHA), the immunoglobulin (IgG)-fluorescent T. pallidum absorption assay (IgG-FTA-ABS), and the Venereal Disease Research Laboratory (VDRL) test. In addition, some seropositive samples were analyzed by the 19S-IgM-FTA-ABS test, an enzyme immunoassay (IgM-EIA), and the MarDx immunoblotting assay. Based on a consensus diagnosis derived from conventional serology, all of the sera were classified as positive, negative, or indeterminate, and the results were compared with the findings of the INNO-LIA Syphilis assay. The sensitivity and specificity of the LIA were 100% (219 of 219) and 99.3% (286 of 288), respectively. Compared to TPHA and IgG-FTA-ABS, the new test gave a significantly higher number (P = 0.021 and P < 0.0001, respectively) of correct results than either of the other two tests. The multiparameter INNO-LIA Syphilis assay is a useful confirmatory test for syphilis because it increases the reliability of syphilis diagnosis with respect to current conventional techniques

Development of a Novel Multiplex Immunoassay Multi-cruzi for the Serological Confirmation of Chagas Disease.

BACKGROUND:Chagas disease is due to the parasite Trypanosoma cruzi, a protist disseminated by a Triatome vector. This disease is endemic to Latin America and considered by WHO as one of the 17 world's neglected diseases. In Europe and in North America, imported cases are also detected, due to migration of population outside of the endemic region. Diagnosis of T. cruzi infection is usually made indirectly by the detection of specific antibodies to T. cruzi antigens. Following initial diagnostic evaluation or screening test (qualifying or discarding blood donation), a confirmation test is performed for samples initially reactive. The test presented in this study aims at the confirmation/refutation of the infectious status of human blood samples and will permit taking appropriate clinical measures. METHODOLOGY/PRINCIPAL FINDINGS:We designed a novel array of twelve antigens and printed these antigens onto 96-well plates. We tested 248 positive samples T. cruzi, 94 unscreened blood donors' samples from non-endemic area, 49 seronegative blood donors, 7 false-positive and 3 doubtful samples. The observed reactivities were analyzed to propose a decision-tree algorithm that correctly classifies all the samples, with the potential to discriminate false-positive results and sticky samples. We observed that antibodies levels (Sum of all antigens) was significantly higher for PCR positive than for PCR negative samples in all studied groups with Multi-cruzi. CONCLUSION/SIGNIFICANCE:The results described in this study indicate that the Multi-cruzi improves the serological confirmation of Chagas disease. Moreover the "sum of all antigens" detected by Multi-cruzi could reflect parasitemia level in patients-like PCR signals does-and could serve as an indicator of parasite clearance in longitudinal follow-ups. Validation of this assay is still required on an independent large collection of well characterized samples including typical false-reactive samples such as Leishmaniasis