Infectivity and in vitro development.

<p><i>In vitro</i> infection assay in Vero cell cultures using Berenice-62 (grey square), Berenice-78 (parental, black square) strains and subpopulations/isolates of Be-78 strain, obtained from hemocultures at 3, 6 or 12 months after infection of Swiss mice with 5000 blood trypomastigotes from Be-78 <i>Trypanosoma cruzi</i> strain. After 18 exposure hours to the parasite, the cells were washed to remove extracellular parasites and maintained in medium until collection, fixation and staining 24 (solid bar), 48 (hatched bar) ou 72 (dotted bar) hours after inoculum. A) number of infected cells in 100 counted cells; B) number of intracellular amastigotes in 100 counted cells; C) number of intracellular parasites per infected cell. *: Significant difference compared to the 24 hours of culture; #: Significant difference compared to the 48 hours of culture; a: significant difference compared to the strain Be-62; b: significant difference compared to the Be-78 parental strain. The data represent the mean of triplicates ± standard error.