Abstract
Visceral leishmaniasis is a reemerging neglected tropical disease with limitations for its diagnosis, including low concentration of antibodies in the serum of asymptomatic patients and cross-reactions. In this context, this work proposes an electrochemical immunosensor for the diagnosis of visceral leishmaniasis in a more sensitive way that is capable of avoiding cross-reaction with Chagas disease (CD). Crude Leishmania infantum antigens tested in the enzyme-linked immunosorbent assay (ELISA) were methodologically standardized to best engage to the sensor. The antibodies anti-Trypanosoma cruzi and anti-Leishmania sp. Present in serum from patients with diverse types of CD or leishmaniasis were chosen. A screen-printed carbon electrode modified with gold nanoparticles was the best platform to guarantee effective adsorption of all antigens so that the epitope of specific recognition for leishmaniasis occurred efficiently and without cross-reaction with the evaluated CD. The current peaks reduced linearly after the recognition, and still were able to notice the discrimination between different kinds of diseases (digestive, cardiac, undetermined Chagas/acute and visceral chronic leishmaniasis). Comparative analyses with ELISA were performed with the same groups, and a low specificity (44%) was verified due to cross-reactions (high number of false positives) on ELISA tests, while the proposed immunosensor presented high selectivity and specificity (100%) without any false positives or false negatives for the serum samples from isolated patients with different types of CD and visceral leishmaniasis. Furthermore, the biosensor was stable for 5 days and presented a detection limit of 200 ng mL−1.
Highlights
Leishmaniasis is a complex of diseases caused by a protozoan of the genus Leishmania [1,2]that affects millions of people worldwide
The analyses enabled the evaluation of which platform increased stability andand maintenance of of thethe biological activity ofof the antibody maintenance biological activity the antibodybecause becausethe theimmobilization immobilizationofofthe theprobe probeon theon electrode surface is a crucial step in the development of the sensors
We found that the proposed biosensor detects Chagas disease as being a weak interaction, with this connection being due to the existence of some possible interactions between the total leishmaniasis antigen and the anti-Trypanosoma cruzi antibody that causes Chagas disease
Summary
Leishmaniasis is a complex of diseases caused by a protozoan of the genus Leishmania [1,2]that affects millions of people worldwide. Visceral leishmaniasis, caused by Leishmania donovani and Leishmania infantum, represents the most severe form and can lead to death if not treated [3,4]. The onset of the infection and clinical manifestations are dependent on many factors including environmental and host immunologic status, especially in the early stages of infection [5]. Visceral leishmaniasis represents a major health problem in some tropical areas of the world. The currently available serum diagnosis does not fit the proper criteria of sensitivity and specificity, especially for identification of asymptomatic and or low symptomatic patients due to the low concentration of antibodies in the serum, in the case of asymptomatic patients, which results in high cross-reactions [6]. Due to its epidemiological characteristics, a diagnostic test that is accessible in remote areas is a desired tool for precise diagnosis and early therapeutic intervention
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