Recombinant <scp>LPG3</scp> Protein From <i>Leishmania chagasi</i> as an Antigen for the Diagnosis of Canine Visceral Leishmaniasis

Visceral leishmaniasis (VL) is a human neglected tropical disease in which dogs participate as reservoirs of the etiological agent Leishmania chagasi. The identification of infected dogs is important to the control of VL, and recombinant proteins are strong antigen candidates for canine visceral leishmaniasis (CVL) serodiagnosis. In this work, we evaluated the enzyme-linked immunosorbent assay (ELISA) using the L. chagasi LPG3 recombinant protein (rLPG3) as an antigen for the CVL diagnosis. The tests were performed on 242 serum samples and showed a remarkable 95.71% sensitivity and 87.50% specificity, with cross-reactivity observed in some samples positive for Ehrlichia canis and Trypanosoma cruzi. The performance of the rLPG3-ELISA test was similar to the performance of IFI-CVL and IFI-CVL plus ELISA-CVL Bio-Manguinhos tests, widely used in the diagnosis of CVL in Brazil, and presented better sensitivity results compared to those obtained in rapid tests available for CVL using other antigenic proteins. Further refinement is necessary to minimize the cross-reactivity and enhance the specificity of the test. Studies to discriminate cross-reactive epitopes of rLPG3, particularly those shared with E. canis protein sequences, may help improve diagnostic accuracy by excluding these epitopes from the detection reaction.