BAG1 and cyst: Among the 189 cyst-wall positive hybridomas, we identified an mAb clone SalmonE that reacted with bradyzoite-containing parasitophorous vacuoles and uniformly stained the limiting parasitophorous vacuole membrane of BAG1-positive parasites (bradyzoites) but did not stain vacuoles containing BAG1 negative parasites (Figure 1A).