Identification of biomarkers for Chagas disease

Wednesday, October 26, 2011 — Poster Session IV
2:00 p.m. – 4:00 p.m.	Natcher Conference Center	FDA/CBER	INFECTDIS-9

Authors

• R Nagarkatti
• FF de Araujo
• C Gupta
• A Debrabant

Abstract

To overcome the difficulty of detecting Chagas parasites (Trypanosoma cruzi) in blood, diagnostic assays detect host anti-T. cruzi antibodies as a surrogate marker for infection. However, these assays are not always reliable. Previous studies show that the parasites secrete various antigens in the blood, termed as T. cruzi Excreted Secreted Antigens (TESA). We used in-vitro SELEX methods to develop TESA specific RNA ligands (aptamers). The TESA SELEX was performed using infected NIH-3T3 cell culture supernatant. Biotinylated monoclonal aptamers were utilized in an enzyme linked assay to detect specific interaction with TESA antigens and T. cruzi infected mouse plasma. Based on their binding activity to TESA aptamers were selected for further analysis. Aptamer L44 (AptL44) demonstrated a consistent interaction with infected mouse plasma. This interaction was specific as a scrambled aptamer did not bind to either infected or uninfected mouse plasma. AptL44 was also able to detect TESA in chronically infected mice, 135dpi where no parasites were detectable in blood. Further analysis of the binding properties of AptL44 and the identification and purification of its target are being carried out. This is the first demonstration of an aptamer based assay that detects a parasite biomarker for the diagnosis of Chagas disease.

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