CST1 and cyst: T. gondii bradyzoite antigen 1 (BAG1) is a bradyzoite-specific marker (Tomavo et al., 1991), and cyst wall markers [e.g., bradyzoite-specific cyst-wall protein 1 (CST1)], which are markers of bradyzoite differentiation, have also been identified (Zhang and Smith, 1995).