Serological test for detecting all geographical variances of Trypanosoma cruzi infection

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Chagas disease is a neglected tropical disease that is 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 chronic phase. The diagnosis of both phases is challenging as patients can be asymptomatic or have nonspecific symptoms. If untreated, acute infection progresses to a chronic phase where 20 ‒ 40% of patients will develop life-threatening illness, including cardiomyopathy, heart failure and cardiac arrest. Acute infection can be detected by microscopy; however, the level of parasitemia during chronic infection drops below the limit of detection of this technique, making it unsuitable for diagnosis. Therefore, the diagnosis of chronic infection relies mainly on serological detection of anti-T. cruzi antibodies, which 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 differences in the seven T. cruzi discrete typing units (DTUs) subtypes. For these reasons, the WHO and PAHO recommends testing using at least two different serological techniques for diagnosing Chagas infection. In the United States, discordant results obtained 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, the objective of this project is to develop a serological test that can accurately detect all geographical variances of T. cruzi infection. This assay will employ a collection of carefully designed recombinant T. cruzi antigens for highly specific detection of all T. cruzi subtypes while exhibiting no cross-reactivity with other pathogens. 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 human sera from multiple Chagas-endemic countries and highly sensitive detection of anti-T. cruzi IgG in human sera using a magneto immunoassay prototype. To achieve this goal, we will pursue the following specific aims: 1) Identify a collection of recombinant antigens for detecting all T. cruzi subtypes with high specificity; 2) Develop a magneto immunoassay for high sensitivity and specificity detection of T. cruzi. This approach is innovative because it combines the use of a collection of carefully designed recombinant T. cruzi antigens for detecting all geographic subtypes of T. cruzi while exhibiting no cross-reactivity with other parasites with a sensitive magneto immunoassay, and it is significant because it will improve the diagnosis of patients with chronic Chagas disease, thus helping to reduce disease-related morbidity and mortality.