Aptamer-based detection of disease biomarkers in mouse models for chagas drug discovery.

Fernanda Fortes De Araujo,Charu Gupta,Rana Nagarkatti,Alain Debrabant,Ana Paula Marino,Michael P Pollastri

doi:10.1371/journal.pntd.0003451

Abstract

Drug discovery initiatives, aimed at Chagas treatment, have been hampered by the lack of standardized drug screening protocols and the absence of simple pre-clinical assays to evaluate treatment efficacy in animal models. In this study, we used a simple Enzyme Linked Aptamer (ELA) assay to detect T. cruzi biomarker in blood and validate murine drug discovery models of Chagas disease. In two mice models, Apt-29 ELA assay demonstrated that biomarker levels were significantly higher in the infected group compared to the control group, and upon Benznidazole treatment, their levels reduced. However, biomarker levels in the infected treated group did not reduce to those seen in the non-infected treated group, with 100% of the mice above the assay cutoff, suggesting that parasitemia was reduced but cure was not achieved. The ELA assay was capable of detecting circulating biomarkers in mice infected with various strains of T. cruzi parasites. Our results showed that the ELA assay could detect residual parasitemia in treated mice by providing an overall picture of the infection in the host. They suggest that the ELA assay can be used in drug discovery applications to assess treatment efficacy in-vivo.

Highlights

Chagas disease (CD) is prevalent across various countries in Central and South America, with 28 million people at risk of getting infected [1,2]
Our study shows that high biomarker levels in T. cruzi infected mice, after drug treatment, can indicate treatment failure
Our assay provides a global picture of parasitemia in the host and a positive result would suggest that the treated animals continue to harbor T. cruzi parasites somewhere in the body

Summary

Introduction

Chagas disease (CD) is prevalent across various countries in Central and South America, with 28 million people at risk of getting infected [1,2]. The etiological agent of CD, Trypanosoma cruzi, has two life cycle stages in the infected host, an extracellular trypomastigote form that circulates in blood of infected individuals, and an intracellular amastigote form that is present in the infected tissues and organs, such as the heart [3,4]. It has been estimated that for chronic individuals.80% of treated patients do not demonstrate parasitological cure and in the absence of drug therapy, or in immuno-compromised patients, recurrence of parasitemia is common [11,12]. In light of these issues associated with CD therapy, new and better drugs need to be developed

Results

Discussion

Conclusion