Trypanosoma cruzi: selective isolation of pure trypomastigotes from cultured muscle cells.

Trypomastigote or trypomastigote-amastigote populations of Trypanosoma cruzi (Y strain, MERC 2C) entirely free of epimastigotes were obtained from infected muscle cell cultures, and separated from host-cell debris by passage through a DEAE-cellulose column. Approximately 75% of the parasites were recovered and mouse infectivity titrations with postcolumn trypomastigotes showed only a slight reduction in infectivity compared to starting material. Light and electron microscopic examination of material showed a high degree of purity had been achieved by the column procedure. No host-cell debris could be identified in the eluate and parasites were morphologically intact. Enumeration of trypomastigotes and amastigotes in mixed populations before and after column purification showed that there was no preferential loss of either stage and both had the same residence time. This procedure may be used to obtain clean, minimally altered, parasite material free of the invertebrate epimastigote stage and host-cell debris for studies which are sensitive to these contaminants.