Figure 4.

GRA17 is important for bradyzoite viability of the ME49 strain. Confluent monolayers of HFF were infected with indicated strains at a MOI of 0.2 and incubated under stage-conversion conditions for 7 or 14 days. (A) The samples were fixed and at least 50 vacuoles were classified as DBA-positives or DBA-negative. (B) The average number of vacuoles per field were counted (P < 0.0001). (C) Bradyzoites were isolated from the 7- and 14-day-old in vitro cysts that were treated with pepsin to kill all tachyzoites. Confluent monolayers of HFFs were infected with 5 × 10³ bradyzoites and 8 days later the number of plaques formed were counted and the average number of plaques was normalized to wild type. Bars represents the averages of biological replicates (n = 4) and error bars represent SD. Unpaired Student's t-tests were performed comparing each strain with the wild type to assess statistical significance. ***p = 0.00012. (D) As in (C) but bradyzoites were isolated from the 7-day-old in vitro cysts switched under 5% of CO₂. Bars represents the averages of biological replicates (n = 3) and error bars represent SD. Unpaired Student's t-tests were performed comparing each strain with the wild type to assess statistical significance. ***p = 0.00017, **p = 0.0041.