The FML (Fucose Mannose Ligand) of Leishmania donovani. A new tool in diagnosis, prognosis, transfusional control and vaccination against human kala-azar

Abstract

The Fucose-Mannose Ligand (FML) of Leishmania donovani is a complex glycoproteic fraction. Its potential use as tool for diagnosis of human visceral leishmaniasis was tested with human sera from Natal, Rio Grande do Norte, Brazil. The FML-ELISA test, showed 100% sensitivity and 96% specificity, identifying patients with overt kala-azar (p < 0.001, when compared to normal sera), and subjects with subclinical infection. More than 20% apparently healthy subjects with positive reaction to FML developed overt kala-azar during the following 10 months. In the screening of human blood donors, a prevalence of 5% of sororeactive subjects was detected, attaining 17% in a single day. The GP36 glycoprotein of FHL is specifically recognized by human kala-azar sera. The immunoprotective effect of FML on experimental L. donovani infection was tested in Swiss albino mice. The protection schemes included three weekly doses of FML, supplemented or not with saponin by the subcutaneous or intraperitoneal routes and challenge with 2 x 107 amastigotes of Leishmania donovani. An enhancement of 80.0% in antibody response (p < 0.001) and reduction of 85.5% parasite liver burden (p < 0.001) was detected in animals immunized with FML saponin, unrespectively of the immunization route.