Demonstration of an On-Chip Real-Time PCR for the Detection of Trypanosoma Cruzi

Abstract

Discovered in 1909, Chagas disease, caused by the parasite Trypanosoma cruzi, continues to be an important tropical disease in Latin America and Caribbean, affecting more than 7 million people. Recently, Chagas disease has also been reported in US and Europe mainly because of unscreened blood donations by immigrants from endemic areas. Current Chagas disease diagnostic relies on search for parasites on blood smears using optical microscopes, screening for serological response, xenodiagnosis, hemoculture and, more recently, polymerase chain reaction (PCR). Each of these tests has its own problems, mainly because of the changes in the immunological profile of the patients and number of circulating parasites in the blood throughout the evolution of the disease. In endemic areas, logistic issues are an additional difficulty for delivering the results to the patients, so a rapid and sensitive point of care test is desirable. In this work, we present results of an on-chip test able to detect equivalent amounts of parasites’ DNA such as those typically present in both acute and chronic phase of the disease. We developed a silicon chip-based PCR using a portable thermocycler with fluorescent detectors that has many advantages over the conventional PCR. When compared to the conventional PCR, our on-chip reaction shows similar sensitivity (between 1 and 0.1 genome equivalents), but a shorter reaction time (35 min versus 90 min). The results presented herein are the first step towards the development of a portable diagnostic test using a fast, sensitive and specific reaction for the detection of Trypanosoma cruzi.