Biomarker Discovery for Point-of-Care Diagnostics

Abstract

Infectious diseases have caused billions of deaths in the last 200 years. Significant gaps persist in diagnosis, treatment, and eradication of nearly all infectious diseases. Identification of novel biomarkers addresses this gap by providing targets for diagnostics, treatments, disease monitoring, vaccines, and prognoses. Proteomics and metabolomics are two broad analytical approaches for biomarker discovery methodologies. In the following studies, varying methods are applied to two unique infectious diseases, tuberculosis and Chagas disease, for identification of novel biomarkers. Chagas disease (CD), caused by Trypanosoma cruzi (T. cruzi) protozoa, is a complicated parasitic illness with inadequate medical measures for diagnosing infection and monitoring treatment success. To address this gap, we analyzed changes in the metabolome of T. cruzi infected mice via liquid chromatography tandem mass spectrometry of two clinically accessible biofluids: urine and plasma. Metabolites perturbed by infection in urine include kynurenate, acylcarnitines, and threonylcarbamoyladenosine. Based on these results, we sought to implement urine as a tool for the assessment of CD treatment success. Strikingly, it was found that mice with parasite clearance following benznidazole (Bz) antiparasitic treatment had an overall urinary metabolome comparable to that of mice that failed to clear parasites. These results provide a complementary hypothesis to explain clinical trial data in which Bz treatment did not improve patient outcomes in late-stage disease, even in patients with successful parasite clearance. Overall, this study provides insights into new small-molecule-based CD diagnostic methods and a new approach to assess functional responses to treatment. Tuberculosis (TB), caused by the bacillus Mycobacterium tuberculosis (Mtb), is a serious airborne disease that has claimed more than one billion lives. Serious gaps persist worldwide in rapid diagnosis and completion of treatment, despite treatments with high cure rates being available. Communities lacking appropriate economical and health resources often suffer the most, and rapid, point-of-care diagnostics are the first step in relieving the global TB disease burden. We utilized a novel rabbit model to analyze circulating antigens in serum and urine to identify six potential protein biomarker candidates. IgG antibody-producing hybridomas were developed to one of the identified targets for potential use in a point-of-care diagnostic assay format. Taken together, these studies support the utilization of multiple methodologies, such as proteomics and metabolomics, to gain valuable insights for development of point-of-care diagnostics for infectious diseases.