Trypanosoma cruzi: Interaction with Vertebrate Cells. DNA Synthesis and Growth of Intracellular Amastigotes and their Relationship to Host Cell DNA Synthesis and Growth

Abstract

DNA synthesis of intracellular T. cruzi amastigotes, following the infection of bovine embryo skeletal muscle (BESM) cells, was studied by autoradiography. After penetration, there was a prereplicative lag period (.apprx. 12 h) followed by a synchronous round of DNA synthesis, which was independent of parasite number/BESM cell and the host cell DNA synthesis cycle. Parasite reproduction occurred, for the 1st time, at .apprx. 21 h postinfection. T. cruzi trypomastigotes are in the G1/G0 phase of their cell division cycle and after penetration parasite reproduction occurs independent of events controlling host cell DNA synthesis and growth. The early synchronous growth of intracellular amastigotes should facilitate further studies on the biochemical events controlling trypomastigote-to-amastigote transformation and amastigote reproduction. A further application is envisaged for studies on the mode of action of drugs with trypanocidal activity.