OPN1LW and cyst: In addition, genetic deletion of several Toxoplasma rhoptry (ROP) or IVN-associated GRA proteins was recently shown to markedly reduce cyst burdens (47, 50, 66, 69), Here, we show that deletion of GRA2, GRA4, GRA6, GRA9, and GRA12, but not GRA1, reduced DBA staining intensity at the cyst periphery relative to the cyst interior by day 3 postdifferentiation.