To determine if ROCY1 was important for DBA+ cyst formation in vivo, we infected CBA/J mice with TgVEG WT-GFP-LUC, TgVEGΔROCY1-GFP-LUC, and TgVEGΔBFD1-GFP-LUC parasites in two separate experiments and monitored pathogenesis, morbidity and mortality using weight loss and in vivo bioluminescence imaging. This evidence concerns the gene RPS19 and cyst.