Trypanosoma cruzi: identification of a galactose-binding protein that binds to cell surface of human erythrocytes and is involved in cell invasion by the parasite

Abstract Trypanosoma cruzi must invade mammalian host cells to replicate and complete its life cycle. Almost all nucleated mammalian cells can be invaded by the parasite following a receptor–ligand recognition as an early prerequisite. In this work, we describe a 67-kDa lectin-like glycoprotein that binds to desialylated human erythrocyte membranes in a galactose-dependent way. This protein is present on the parasite surface in both infective and non-infective stages of T. cruzi . More interestingly, we demonstrate by lectin-immuno-histochemistry assays that the 67 kDa protein is involved in the recognition of host-cell receptors in mouse cardiac tissue and human cardiac aortic endothelium and mammary artery tissue. Moreover, antibodies against the 67 kDa glycoprotein inhibit in vitro host-cell invasion by 63%. These data suggest that the 67 kDa glycoprotein in vivo is needed for host-cell invasion by T. cruzi. Index Descriptors and Abbreviations: Trypanosoma cruzi ( T. cruzi ), Red blood cell membranes, 67-kDa lectin-like glycoprotein (LLGP-67), Shed acute phase antigen (SAPA), Red blood cell ghosts (RBCG), Lythium diiodesalicylate (LIS), Total homogenate (TH), Phosphate buffered saline (PBS), Phosphate saline buffer, 0.01% Tween 20 (PBS-T), Phenylmethylsulphonyl fluoride (PMSF), N α- p -Tosyl- l -lysinechloromethyl ketone (TLCK), Ultraviolet (UV), Concanavalin A (Con A), Peanut agglutinin (PNA), Tetramethylbenzidine (TMB), Sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE), Enzyme-linked immunosorbent assay (ELISA), Immunofluorescence asssay (IFA), Bovine serum albumin (BSA), Indirect hemagglutination assay (IHA), Dimethyl sulphoxide (DMSO).