TRANS-SIALIDASE AND SIALIDASE ACTIVITIES DISCRIMINATE BETWEEN MORPHOLOGICALLY INDISTINGUISHABLE TRYPANOSOMATIDS

The expression of trans-sialidase and sialidase activities in the kine toplastid protozoa was explored as a potential marker to discriminate between the morphologically indistinguishable flagellates isolated fro m human, insects and vertebrate reservoir hosts. By virtue of the diff erences observed in the ratios of these enzyme activities, a collectio n of 52 species and strains comprising the major taxa of these parasit es could be separated into four expression types. Type-I parasites exp ress comparable levels of both trans-sialidase and sialidase activitie s (Endotrypanum species and Trypanosoma lewisi). Type-II parasites exp ress predominantly trans-sialidase activity (Trypanosoma cruzi and Try panosoma conorhini). Type-III parasites express sialidase activity exc lusively (Trypanosoma rangeli and Trypanosoma leeuwenhoeki). Type-IV p arasites do not express either activity (Leishmania species and Trypan oplasma borreli). The measurement of trans-sialidase and sialidase act ivities thus permits the differentiation of parasites frequently found in the same insect vectors that are difficult to distinguish, such as T. cruzi and T. rangeli, or in the same sylvatic vertebrate and inver tebrate hosts, such as Leishmania and Endotrypanum.