The characterization of Trypanosoma cruzi stocks by starch-gel electrophoresis, comparison of results with those of isoelectric focusing.

Abstract

The culture forms of 30 T. cruzi stocks originating from different parts of Brazil and Venezuela were screened by starch-gel electrophoresis for the isoenzyme patterns of 9 enzymes: glucose-6-phosphate dehydrogenase (G6PD), phosphoglucomutase (PGM), glucosephosphate isomerase (GPI), aspartate aminotransferase (ASAT), "malic" enzyme (ME), alanine aminotransferase (ALAT), peptidases (PEP 1, PEP 2) and malate dehydrogenase (MDH). G6PD, PGM, GPI to some extent also ASAT, ME patterns divide 25 stocks into two distinct main groups A and B. The Brazilian stocks of group A originated from different wild animal species only, those of group B were with one exception isolated from human patients, or domestic hosts. In contrast all stocks from Venezuela regardless of their original host belonged to group A. The results of all enzymes showed group A (16 stocks and 7 profiles) to be more homogeneous than group B (9 stocks and 7 profiles). Comparison of these results with previous results of isoelectric focusing of the same stocks shows both methods to be complementary. The two methods gave identical classification of stocks with G6PD, PGM and GPI, both methods dividing most stocks into two main groups. The enzymes ALAT and ASAT confirmed this grouping to some extent in the starch-gel electrophoresis. For both starch-gel and isoelectric focusing ME was of only limited value because of variable enzyme activities in the trypanosome extracts. For the enzymes PEP 1, and PEP 2 and MDH neither method was useful in demonstrating intraspecific variation within the T. cruzi complex.