Enhanced diagnostic tools for visceral leishmaniasis using kinase based antigens in Brazilian human and canine samples.

Visceral leishmaniasis (VL), caused by Leishmania infantum, is a major public health concern in Brazil, with domestic dogs as key reservoirs. Accurate diagnosis is crucial, but current tools like rK39 have limited sensitivity and regional variability. This study evaluated three recombinant kinase antigens-Repressor of Differentiation Kinase 2 (RDK2), Aurora I-related kinase (LdAIRK), and Activated C Kinase Receptor (LACK)derived from Leishmania donovani for their diagnostic potential in canine VL (CanL) and RDK2 in human VL. These antigens were selected based on amastigote-stage expression, conservation among virulent strains, and low homology with host proteins or co-endemic pathogens. Using computational prediction, and immunoproteomics, antigens were expressed and further validated via ELISA and dipstick assays. Serum samples from humans (VL, n = 40; controls, n = 19) and dogs (CanL, n = 36; controls, n = 36) were collected in Teresina, Brazil. RDK2 showed (90% sensitivity, 78.95% specificity) for human VL, while LdAIRK showed the highest diagnostic accuracy for CanL (88.89%, 97.22%), followed by LACK and RDK2. Dipstick tests confirmed these findings, offering rapid, field-friendly alternatives and demonstrating enhanced performance compared to two reference rK39 tests, pending broader comparative validation. LdAIRK emerged as a promising diagnostic marker for CanL, with the potential to enhance VL control in endemic regions.