A surface antigen of Trypanosoma cruzi involved in cell invasion (Tc-85) is heterogeneous in expression and molecular constitution.

A monoclonal antibody (McAb), H1A10, causes 46-96% inhibition of the invasion of tissue culture cells by trypomastigotes from different strains and clones of Trypanosoma cruzi. Higher inhibition was observed when axenic medium-derived metacyclic trypomastigotes (72-96%) were employed instead of tissue culture-derived trypomastigotes (46-60%). In contrast to the metacyclic population, in which all individuals reacted with the McAb, part of the tissue-cultured trypomastigote population did not bind the antibody. The molecular masses and isoelectric points of the glycoproteins recognized by the H1A10 McAb differed when tissue culture trypomastigotes of the Y strain and YuYu strain were analyzed. Variability between the strains was also observed when the antigens were metabolically labelled in the presence of tunicamycin. These results suggest that the differences described are probably not due solely to the carbohydrate portion of the molecule.