Trypanosoma cruzi: Interaction with vertebrate cells in vitro: I. Individual interactions at the cellular and subcellular levels

Abstract

Individual interactions between Trypanosoma cruzi trypomastigotes and vertebrate cells were observed in vitro as a continuous function of time under highly controlled environmental conditions. These observations form the basis for a description of the complete intracellular cycle of T. cruzi in susceptible vertebrate cells. Trypomastigotes actively penetrated the vertebrate cells. Multiple penetrations of a single cell were observed. A highly variable “lag period” occurred prior to the onset of parasite reproduction. This “lag period” was identical in two different host cell types. Amastigotes reproduced asynchronously, and the number of parasites produced in the host cell was directly proportional to the number of trypomastigotes penetrating the cell. The differentiation of amastigotes to trypomastigotes occurred by a direct “fusiform progression” pathway. The escape of trypomastigotes from the dead host cell occurred approximately 6.5 days post infection of the cell. Trypomastigotes were capable of infecting a vertebrate cell immediately after escaping from the cell in which they had completed their life cycle.