A preliminary comparison of Trypanosoma simiae and T. congolense by isoenzyme electrophoresis.

Trypanosoma simiae, although similar to T. congolense in morphology and mode of development in the tsetse vector, is regarded as a separate species mainly because it is highly pathogenic to the domestic pig and fails to infect rodents. To establish whether the two species are distinct biochemically, we compared by isoenzyme electrophoresis 2 isolates of T. simiae with 7 stocks of T. congolense, together with one of T. brucei. All isoenzyme patterns of the 6 enzymes examined differed in T. simiae from T. congolense and T. brucei stocks. This supports the designation of T. simiae as a separate species. However, a comparison involving a much larger collection of T. simiae is necessary in order to get conclusive evidence.