Development and validation of a recombinant chimeric antigen based on Leishmania infantum B-cell epitopes for canine serology.

This study describes the development and validation of a novel multi-epitope chimeric protein (rChi) for the serodiagnosis of canine leishmaniasis caused by Leishmania infantum (CanL). The rChi construct was engineered based on B-cell epitopes from hypothetical proteins previously identified through immunoproteomic profiling. To evaluate its diagnostic performance, an indirect ELISA was conducted using a comprehensive panel of canine serum samples (n = 291), including clinically affected, subclinically infected, and non-infected dogs, as well as Leish-Tec®-vaccinated animals and those infected with potentially cross-reactive pathogens (Babesia vogeli, Ehrlichia canis, and Trypanosoma cruzi). The rChi-ELISA demonstrated superior diagnostic parameters compared to L. infantum soluble Leishmania antigen (SLA), achieving 92.2% sensitivity and 76.2% specificity (AUC = 0.85; Accuracy = 80.8%), whereas SLA showed only 50.0% sensitivity and 68.3% accuracy. These findings indicate that the rChi protein significantly enhances CanL detection and represents a promising tool for more accurate veterinary diagnostics and surveillance.