Fig 4.

Parasite replication in trophoblasts within placental explants relative to replication in HFF. (A) Representative examples of parasitic vacuole sizes after 24-h or 48-h infection in HFF. Green, GFP-expressing type I T. gondii; white, DNA; red (outside), anti-SAG1 (stained parasites), added without permeabilization (none visible here). Bar, 10 μm. (B) Number of parasites per vacuole was scored in placental histological sections (top) or HFF cells (bottom) at 24 and 48 h p.i. Each bar represents the average of three placentas or HFF samples. The P value (between graphs) denotes the result of t tests comparing placenta and HFF percentages of single-parasite vacuoles across the three samples. (C) The log₂ transformation of parasites/vacuole yields the average number of replications per parasite in HFF and placenta samples from 24 to 48 h for each parasite type (calculated from data in panel B). Of note, panel C gives logarithmically greater weight to larger vacuoles in comparison to panel B: 1-parasite vacuoles have not replicated and thus received scores of zero, while 4-parasite vacuoles were weighted twice as heavily as 2-parasite vacuoles and 8-parasite vacuoles received three times the 2-parasite weight. Some cell lysis occurred by 48 h for type I (see Materials and Methods). Bars, SEM.