Heterogeneous distribution of neuraminidase activity in strains and clones of Trypanosoma cruzi and its possible association with parasite myotropism.

Various strains, stocks, and clones of Trypanosoma cruzi were analyzed for neuraminidase (NA) activity using fetuin and human erythrocytes as substrate. In all cases the activity was found to be developmentally regulated. Zymodeme type I strains, which are histotropic for skeletal muscle, had greater NA activity than zymodeme type II strains which are histotropic for either macrophages or cardiac muscle cells. Heterogeneity of NA expression within strains is suggested by the finding that one Silvio X10 clone had greater NA activity than another clone of the same stock. The differences observed were more pronounced when human erythrocytes and not fetuin were used as substrate. Trypomastigotes of the high producing strains reared in bovine artery smooth muscle cells had enhanced expression compared to trypomastigotes reared in 3T3 or human fibroblast cells. The first harvest of trypomastigotes from cell cultures had greater NA activity than trypomastigotes harvested on subsequent days.