In this work we have studied the modifications in the biological
properties of Trypanosoma cruzi when the parasite is
maintained for a long time in axenic culture. The studies were done
with a clone from an avirulent strain (Dm30L) and a non-cloned
virulent strain (EP) of T. cruzi. Both parasites were
maintained, for at least three years, by successive triatomine/mouse
alternate passage (control condition), or by serial passage in
axenic medium (culture condition), or only in the mouse (mouse
condition). The comparison between parasites of culture and control
condition showed that metacyclogenesis capacity was reduced in the
former and that the resulting metacyclics displayed an attenuated
virulence. In order to compare the virulence of metacyclics from the
urine of the insect vector, Rhodnius prolixus were infected
by artificial feeding with parasites of the control or culture
condition. After three triatomine/triatomine passages, there was
observed an almost identical biological behavior for these
parasites, hence indicating that the maintenance of T. cruzi
for a long time in axenic culture affects the differentiation
capacity and the virulence of the parasite. Additionally, it was
demonstrated that it is possible to maintain T. cruzi
exclusively through passages in the invertebrate host.