Figure 5. Detection of T. gondii tachyzoites in RAW macrophages following a 24-h co-incubation period with native T. gondii oocysts.

Following oocyst co-incubation, macrophage or HFF cells were fixed and permeabilized with methanol and tachyzoites were detected by using a tachyzoite specific SAG1 polyclonal antibody. (A) Semi-quantification of the number of parasitophorous vacuoles (PV) detected in RAW cells or HFF cells from four independent experiments. HFF cells incubated with oocysts, either pre-incubated at 37 °C for 24 h or not, served as controls for possible sporozoite excystation in absence of phagocytosis by RAW cells, as described in the materials and methods section. (B) Distribution of the number of tachyzoites detected per PV (over ~50 PV counted) in RAW cells incubated with native oocysts for 24 h **p < 0.01. (C) Representative images of tachyzoites identified in RAW cells. Scale bars = 5 μm.