Real-time RT-PCR of Hsp90 transcriptional level during bradyzoite differentiation in vitro. The RHΔku80 T. gondii cells were exposed to alkaline treatment (pH 8.1) (A) or heat shock (41 °C) (B) for 0, 24, 48, 72 or 96 h. Total RNA was purified from the bradyzoites collected at the end of each time point. The expression levels were determined by real-time RT-PCR using actin as an internal control. Samples collected at 24, 48, 72 or 96 h were compared to those at time 0 h. “***” indicate a statistically significant difference (p < 0.001). Values represent mean ± SD, n = 3 experiments.