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Some enzymes produced by the protozoon Leishmania can have an important role in the intraphagocytic survival of the parasites. The production of hydrolytic enzymes by promastigotes belonging to two Leishmania sp. (major and infantum) and maintained in different experimental conditions was evaluated. The proteolytic activity was moderate, while superior was the production of acid phosphatase in L. infantum. An increase of the trypsin-like activity was observed after incubation of protozoa for 24 h at 37 degrees C, while a mouse injection did not changed the enzymatic activity of L. major.

A morphological and chemical transformation of the protozoon Leishmania results during the shift from sand fly vector to mammalian host. This is due to the increase in temperature from about 26 degrees to about 35 degrees C. We evaluated the modifications induced by 37 degrees C on stationary phase promastigotes of two different Leishmania species (L. major and L. infantum). L. infantum changed to amastigote-like forms in a greater and quicker way than L. major; this fact could relate with the more elevated spreading capacity of this species in the human body.