A fraction of type II strains vacuoles spontaneously differentiate to bradyzoites in normal culture conditions, as evidenced by SAG2Y expression on the parasite surface and labeling of the tissue cyst walls with Dolichos biflorus agglutinin (DBA), which recognizes O-linked N-acetylgalactosamine moieties on wall proteins (e.g., CST1) (12). The gene discussed is CST1; the disease is cyst.