High resolution capillary western blot analysis of antibody reactivity in human visceral leishmaniasis.

Visceral leishmaniasis (VL) is a potentially fatal disease, occurring in 76 countries, 12 of which are located in the Americas, with approximately 3,500 new cases annually registered in Brazil. Active visceral leishmaniasis is characterized by an intense inflammatory reaction with a low cell-mediated immune response and a high production of specific and non-specific antibodies. Antibodies are not associated with effective protective mechanisms but have been used widely in diagnostic tests. In this study, we analyzed the immunoglobulin G (IgG) response against crude antigens of Leishmania infantum by using automated western capillary blot in patients with active and clinically cured VL, individuals residing in an endemic area and patients with Chagas disease. The method allowed an accurate analysis of the antibody response. Our results demonstrated that antibody reactivity to L. infantum antigens in the 20-142 kDa range effectively distinguished active VL from clinically cured cases and Chagas disease, although these antigens were not exclusively recognized by patients with active VL. The automated western capillary blot proved to be a useful tool for differentiating patients with active VL from individuals living in endemic areas and those with Chagas disease, highlighting its potential application in serological diagnostics.