A Lectin fromDioclea violaceaInteracts with Midgut Surface ofLutzomyia migonei, Unlike Its Homologues,Cratylia floribundaLectin andCanavalia gladiataLectin

Abstract

Leishmaniasis is a vector-borne disease transmitted by phlebotomine sand fly. Susceptibility and refractoriness toLeishmaniadepend on the outcome of multiple interactions that take place within the sand fly gut. Promastigote attachment to sand fly midgut epithelium is essential to avoid being excreted together with the digested blood meal. Promastigote and gut sand fly surface glycans are important ligands in this attachment. The purpose of the present study was to evaluate the interaction of three lectins isolated from leguminous seeds (Diocleinae subtribe), D-glucose and D-mannose-binding, with glycans onLutzomyia migoneimidgut. To study this interaction the lectins were labeled with FITC and a fluorescence assay was performed. The results showed that onlyDioclea violacealectin (DVL) was able to interact with midgut glycans, unlikeCratylia floribundalectin (CFL) andCanavalia gladiatalectin (CGL). Furthermore, when DVL was blocked with D-mannose the interaction was inhibited. Differences of spatial arrangement of residues and volume of carbohydrate recognition domain (CRD) may be the cause of the fine specificity of DVL for glycans in the surface onLu. migoneimidgut. The findings in this study showed the presence of glycans in the midgut with glucose/mannose residues in its composition and these residues may be important in interaction betweenLu. migoneimidgut andLeishmania.