Evaluation of a novel Tc-24 ELISA test in post-treatment efficacy for Chagas disease.

PROJECT SUMMARY Chagas disease is a neglected tropical disease endemic to Latin America but is increasingly being detected in the United States. Chagas disease is caused by the Trypanosoma cruzi (T. cruzi) parasite and presents itself in two phases: an acute phase and a chronic phase. The diagnosis of both phases is challenging as patients can be asymptomatic or have nonspecific symptoms. If untreated, the acute infection progresses to a chronic phase where 20 ‒ 40% of patients will develop life-threatening illnesses, including cardiomyopathy, heart failure, or cardiac arrest. Acute infection can be detected by microscopy; however, the level of parasitemia during chronic infection often drops below the limit of detection of these techniques, making it unsuitable for diagnosis. Therefore, the diagnosis of chronic infection relies solely on serological detection of anti-T. cruzi antibodies can persist in the blood throughout the life of the infected individual. However, existing serological tests are prone to inconclusive or false-negative/positive results due to inadequacies of the native T. cruzi capture proteins used in these assays and for differences in the six discrete typing units (DTU) subtypes. For this reason, the WHO and PAHO recommend testing using at least two different serological techniques to diagnose Chagas infection. In the United States, discordant results from these two tests require the sample to be forwarded to the CDC for additional testing to confirm diagnosis. This repetitive testing process imposes a significant resource burden on the healthcare system, and the poor performance of existing Chagas serological tests can lead to increased disease transmission and life-threatening illness due to misdiagnosis. Therefore, this project aims to develop and validate a highly sensitive serological assay for detecting all geographic variances of T. cruzi infection with a single test. This assay will employ a collection of carefully designed recombinant T. cruzi antigens, enabling high-sensitivity detection of all T. cruzi strains. The rationale for the proposed research is supported by the applicants’ preliminary data demonstrating the generation of a recombinant T. cruzi antigen (Tc24) that can accurately detect anti-T. cruzi IgG in patient samples from multiple Latin American countries and to provide a test-of-cure in a prospective longitudinal post-treatment study. To achieve this goal, we will pursue the following specific aims: 1) Optimize a Chagas Tc24 Direct ELISA and high repetitive region quantitative PCR for T. cruzi 2) Use Tc24 ELISA and qPCR to provide a proof-of-principle for a test of cure in chronic Chagas This approach is innovative because it combines the use of a collection of carefully designed recombinant T. cruzi antigens for detecting all geographic strains of T. cruzi while exhibiting no cross-reactivity with other parasites with a single test and it is significant because it will provide a test-of-cure and post-treatment efficacy for people with Chagas disease.