Binding of lectin-gold conjugates by two Trypanosoma cruzi strains in ampullae and rectum of Triatoma infestans.

The ampullae and recta of Triatoma infestans infected with Trypanosoma cruzi were incubated with lectin-gold conjugates of wheat germ agglutinin (WGA) and soy bean agglutinin (SBA) and investigated by electron microscopy. T. cruzi colonized the whole lumen of the ampullae. The rectal pads with their intensive intracellular membrane system and thin cuticle were often covered by a compact layer of flagellates, whereas the remaining rectal sac- recognizable by a thick layered cuticle - was colonized less densely. All freely accessible stages of T. cruzi strain 'Chile 5' (Zymodeme 1) showed a reaction with SBA-gold complexes but not with WGA, revealing that N-acetyl-galactosamine and/or galactose but no N-acetyl-glucosamine residues were present on the surface. T. cruzi strain 'Chile 7' (Zymodeme 2) also reacted with SBA. WGA-bovine serum albumin-gold conjugates bound strongly to the surface of epimastigotes of this strain, in variable amounts to stages in transition to trypomastigotes, but not to metacyclic trypomastigotes.