Urine- and serum-based ELISA using a new recombinant chimeric protein to diagnose tegumentary and visceral leishmaniasis: a preliminary study

Abstract

Laboratory diagnosis of leishmaniasis is hampered by the variable sensitivity and/or specificity of the tests. In the present study, we developed a new recombinant antigen based on a chimeric protein, called CHIMISA, which was composed of specific B-cell epitopes from Leishmania antigenic proteins recently identified in an immunoproteomics approach using sera samples from visceral leishmaniasis (VL) and VL/HIV co-infected patients. The protein was produced containing specific B-cell epitopes from four parasite proteins (SUZ41772.1, SUZ41881.1, AYU79515.1, and SUZ44007.1) and used as an antigen in ELISA with serum and urine samples for diagnosing VL, tegumentary leishmaniasis (TL), and VL/HIV co-infection. Paired serum and urine samples from healthy subjects and patients with other cross-reactive diseases were also used. The serum-based CHIMISA ELISA had 100 % sensitivity and 98.5 % specificity for diagnosing VL, TL and VL/HIV, with an area under the (AUC) value of 1.0. Soluble Leishmania Antigenic (SLA) extracts of Leishmania (Viannia) braziliensis and SLA of Leishmania (Leishmania) infantum were used as comparative antigens, and showed sensitivity values of 72.0 % and 44.0 %, respectively, and specificity values of 97.5 % and 98.1 %, respectively. The AUC values were 0.90 and 0.91, respectively. In the urine-based CHIMISA ELISA, sensitivity of 99.0 % and specificity of 98.1 % were reached, with an AUC of 0.99. SLA of L. (V.) braziliensis and SLA of L. (L.) infantum showed 65.6 % and 51.1 % sensitivity, respectively; and 96.9 % and 97.1 % specificity, respectively. The AUC values were 0.91 and 0.86, respectively. Although only a limited serological panel was used in this study, our preliminary data suggest that this new chimeric protein could be considered as a diagnostic candidate for VL, TL, and VL/HIV cases, using patient urine and serum.